A multicopy suppressor screen in yeast to look for negative regulators of Ser13 phosphorylation-based trafficking to the pre-vacuolar compartment

Abstract only availableResident membrane proteins of the yeast trans-Golgi network (TGN) frequently cycle between the TGN and both the early and late (prevacuolar) endosomal compartments. The model yeast TGN protein, A-ALP, which contains the cytosolic domain of the TGN protein, depeptidyl aminopeptidase A (DPAP A), and the transmembrane and lumenal domains of the vacuolar membrane protein, alkaline phosphatase, have been studied. The cytosolic domain of A-ALP has been shown to be phosphorylated in vivo and in vitro. Of the 25 potentially phosphorylatable residues, only one, Ser13, was observed to influence trafficking between the TGN and endosomes. It has been suggested that phosphorylation of Ser13 is required for trafficking of A-ALP from the TGN to the pre-vacuolar compartment, which implies that phosphorylation of Ser13 may act as a switch for association of A-ALP with vesicular trafficking machinery. It is also important to note that once A-ALP reaches the vacuole by way of the PVC, it is cleaved in the lumenal domain, which allows us to follow the trafficking of the protein. We designed a screen to overexpress negative regulators, such as phosphatase, so that A-ALP will exhibit slower trafficking to the pre-vacuolar compartment. Yeast that seemed to have slower A-ALP trafficking to the PVC were identified by an ALP Overlay Assay. These positives are now being screened by western blot in order to verify that these cells exhibit slower trafficking to the PVC and eventually the vacuole. This can be determined by a western blot by examining the amount of processing of A-ALP in the vacuole. Those that are processed less give the indication of slower trafficking to the PVC, which is possibly the result of high phosphatase activity.Life Sciences Undergraduate Research Opportunity Progra

CHARACTERIZATION OF MAGNETIC RESONANCE AND ELECTRICAL PROPERTIES OF POLYVINYL ALCOHOL CRYOGEL

It is not always practical or ethical to use humans for optimization and testing of MR pulse sequences especially when dealing with neonates and children where the MR relaxation parameters (T1 and T2) are substantially different from adults because of the changes in water content during development. Thus5 a tissue mimicking MR phantom would be useful. Polyvinyl Alcohol Cryogel (PVA-C) is a non-toxic material that has been shown to have MR relaxation characteristics similar to aorta5 muscle and fat. To date, no work has been done on the characterization of the electrical properties of PVA-C which could benefit several areas such as matching MR coil loading at high field, and developing a tissue phantom for electrical impedance tomography (EIT). Our objective is to validate PVA-C as a viable phantom material for various human tissues (matching both the MRI and electrical properties). For normal tissue the Ti and T2 values can range from 450ms to 2900ms (for 1.5 T — 3 T) and 40ms to 280ms, respectively. Again for normal tissues, the conductivity ranges from 0.0295 S/m to 0.744 S/m and permittivity ranges from 40 — 400*106. The first experiment involved measuring the relaxation times of PVA-C (made with water) as the %PVA was varied from 3-30% by weight. These samples all underwent 1 ffeeze/thaw cycle (FTC) and the ffeeze/thaw rate (FTR) was kept constant at O.l°C∕minute. The Ti and T2 relaxation times were found to increase with increasing %PVA. At 1.89T the ranges were 0.68 + 0.04

Local Competition, Multimarket Contact, and Product Quality: Evidence From Internet Service Provision

I investigate the effect of competition on quality in the internet service provision industry: I examine both local competition within markets and multimarket contact among firms across markets. This industry offers an ideal setting, as quality is both objective and measurable. I use data from speedtest.net from 2008 to 2014 to estimate a reduced-form model of the effects of local competition and multimarket contact on realized consumer download speeds. I find that increased multimarket contact leads to decreased download speeds, which is consistent with the mutual forbearance hypothesis. I also find that duopolies lead to faster download speeds than do monopolies, but that further increases in the number of competitors decrease speeds

Spatial Variability of Seedling Disease Pressure in Cotton Fields

Seedling diseases are important factors in cotton stand establishment, and seedling disease pathogens are widespread in fields in Arkansas. Little is known about the variability of seedling disease pressure within fields. With expanded adoption of site-specific management and other precision agriculture approaches, cotton producers are increasingly interested in predicting seedling disease pressure, particularly in spatially variable fields. The cotton seedling disease pathogens include the soilborne pathogens Thielaviopsis basicola, Rhizoctonia solani, Pythium spp., and Fusarium spp. These pathogens can survive in soil for long periods and, and when the environment is conducive, these pathogens can act individually or in combination to cause a range of symptoms on seed, roots and hypocotyls, which can affect germination, emergence, and early-season growth and development of plants. Seedling diseases reduce stand density and seedling vigor, which in turn results in variable plant growth and maturity. Results from experiments conducted at the Judd Hill Cooperative Research Foundation in Poinsett Co. Arkansas showed field-scale increases of cotton seedling disease pressure where minimal soil temperature was lower (20.0 °C) and lower seedling disease pressure where minimal soil temperature was higher (21.5 °C) for both years of this study. This study indicates the importance of the role of the environment in disease development and supports the site-specific management zone approaches being adopted by cotton producers

Multi-stage pulse tube cryocooler with acoustic impedance constructed to reduce transient cool down time and thermal loss

The cool down time for a multi-stage, pulse tube cryocooler is reduced by configuring at least a portion of the acoustic impedance of a selected stage, higher than the first stage, so that it surrounds the cold head of the selected stage. The surrounding acoustic impedance of the selected stage is mounted in thermally conductive connection to the warm region of the selected stage for cooling the acoustic impedance and is fabricated of a high thermal diffusivity, low thermal radiation emissivity material, preferably aluminum