Phosphate-mineral interactions and potential consequences for nutrient cycling

Submitted in partial fulfillment of the requirements for the degree of Master of Science at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution June 2008.Biogeochemical cycling of phosphate is a key component in the overall production rate of coastal ecosystems. Mineral phases in the near-shore sediments play a significant role in the return of phosphate remineralized in the upper sediments to the water column. Sequential Extraction (SEDEX) of the solid-phase associated PO4-3 yielded reservoir profiles of phosphate at three sites off of the Massachusetts coast. These extractions found Fe-associated PO4 to be the dominant phase associated with rapid porewater-solid P exchange. Additionally, a seasonal enrichment/depletion pattern of phosphate fluxes relative to total carbon was observed from the sediments. These observations established the behavior of phosphate in coastal sediments as interconnected with the ongoing Fe-cycling in the sediments as well.This work was made possible by sponsorship and funding provided by NOAA, (U.S. Department of Commerce (Grant # NA06OAR4170021, project # R/G-29)); National Science Foundation (Grant # OCE-0526389); WHOI / USGS Cooperative Agreement; and the WHOI Academic Programs Office

Expression and purification of functional human glycogen synthase-1:glycogenin-1 complex in insect cells

We report the successful expression and purification of functional human muscle glycogen synthase (GYS1) in complex with human glycogenin-1 (GN1). Stoichiometric GYS1:GN1 complex was produced by co-expression of GYS1 and GN1 using a bicistronic pFastBac™-Dual expression vector, followed by affinity purification and subsequent size-exclusion chromatography. Mass spectrometry analysis identified that GYS1 is phosphorylated at several well-characterised and uncharacterised Ser/Thr residues. Biochemical analysis, including activity ratio (in the absence relative to that in the presence of glucose-6-phosphate) measurement, covalently attached phosphate estimation as well as phosphatase treatment, revealed that recombinant GYS1 is substantially more heavily phosphorylated than would be observed in intact human or rodent muscle tissues. A large quantity of highly-pure stoichiometric GYS1:GN1 complex will be useful to study its structural and biochemical properties in the future, which would reveal mechanistic insights into its functional role in glycogen biosynthesis

Wiki\u27d Transformations: Technology Supporting Collaborative Learning

This paper examines the uses of wikis in teaching in higher education. It was developed in support of a workshop offered at the Higher Education in Transformation conference in Dublin, Ireland, in March, 2015. The paper describes one author’s use of a wiki over a period of five years to support graduate students in their study of principles of learning, reviews some of the literature on educational applications of wikis and suggests directions for future research

Reproductive Consequences of Obesity

With increasing global obesity, there is a growing body of research looking at the impact of this on reproduction. Both male and female fertility are impacted on by being overweight or obese. Although the pathophysiology is not clear, it appears that obesity impacts endocrine function in men and women, oocyte and sperm quality, embryo quality, endocrine receptivity, and implantation. Miscarriage, pregnancy, and live birth rates and the risk of congenital malformations are all influenced by obesity. Transgenerational health is also affected, with metabolic, endocrine, and reproductive outcomes in the offspring being negatively affected by both paternal and maternal obesity. It appears that weight loss results in improvements in these outcomes and various strategies have been employed including lifestyle and behavior modification, pharmacological agents, and also bariatric surgery. This chapter aims to explore the reproductive outcomes of obesity and how this can be best managed to improve outcomes

An indigobird Vidua sp. puzzle in Uganda

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Hopanoids Play a Role in Membrane Integrity and pH Homeostasis in Rhodopseudomonas palustris TIE-1

Sedimentary hopanes are pentacyclic triterpenoids that serve as biomarker proxies for bacteria and certain bacterial metabolisms, such as oxygenic photosynthesis and aerobic methanotrophy. Their parent molecules, the bacteriohopanepolyols (BHPs), have been hypothesized to be the bacterial equivalent of sterols. However, the actual function of BHPs in bacterial cells is poorly understood. Here, we report the physiological study of a mutant in Rhodopseudomonas palustris TIE-1 that is unable to produce any hopanoids. The deletion of the gene encoding the squalene-hopene cyclase protein (Shc), which cyclizes squalene to the basic hopene structure, resulted in a strain that no longer produced any polycyclic triterpenoids. This strain was able to grow chemoheterotrophically, photoheterotrophically, and photoautotrophically, demonstrating that hopanoids are not required for growth under normal conditions. A severe growth defect, as well as significant morphological damage, was observed when cells were grown under acidic and alkaline conditions. Although minimal changes in shc transcript expression were observed under certain conditions of pH shock, the total amount of hopanoid production was unaffected; however, the abundance of methylated hopanoids significantly increased. This suggests that hopanoids may play an indirect role in pH homeostasis, with certain hopanoid derivatives being of particular importance

Demonstration of a Nano-Enabled Space Power System

The Nano-Enabled Space Power System will demonstrate power systems with nanomaterial-enhanced components as are placement for CubeSat power generation, transmission, and storage. Successful flights of these nano-power systems will accelerate the use of this revolutionary technology in the aerospace industry. The use of nano materials in solar cells, wire harnesses,and lithium ion batteries can increase the device performance without significantly altering the devices physical dimensions or the devices operating range (temperature,voltage, current). In many cases, the use of nanomaterials widens the viable range of operating conditions, such as increased depth of discharge of lithium ion batteries, tunable bandgaps in solar cells, and increased flexure tolerance of wire harnesses