An investigation into the structure and functional aspects of the cell wall of Desulfovibrio

Satisfactory preparations of cell walls from Desulfovibrio vulgaris cells grown in iron rich (C+Fe) and iron poor (C-Fe) media were obtained by partial detergent solubilisation of the cell envelopes. Polyacrylamide gel electrophoresis (PAGE) has shown the presence in the outer membrane (OM) of three major proteins (OMPs l, 2 and 3) and a relatively homogeneous lipopolysaccharide (LPS) containing no ketodeoxyoctonate (KDO). A protein of OMP 1 PAGE mobility is readily removed by the EDTA treatment of cells showing its loose association with the cell surface. Only a portion of OMP l is removed by digestion or acetate extraction indicating the existence of two proteins, OMP la and lb which comigrate in PAGE. 1251 lactoperoxidase labelling of whole cells shows proteins of OMP 1 and 3 mobility to be exposed on the cell surface. OMPs do not show hydrogenase activity and this enzyme is inactive in C-Fe cells. Numerous minor proteins are present in C+Fe OM but are absent from C-Fe OM indicating ’protection’ of the cell wall by iron to detergent solubilisation. In response to iron limitation D.vulgaris Woolwich shows an increase in the proportion of carbohydrate in the cell wall and in the yield of extractable LPS. HPLC studies have shown changes in the LPS sugars with iron limitation indicating an interaction between Fed I) and the LPS. Studies on the release of LPS from Intact cells by an EDTA washing procedure have shown a selective interaction between Fe2+ and LPS In D.vulgaris. Fe(II) appears to have an important role in the stabilisation in vivo of the OM and this selective interaction may play a part in iron uptake. In vitro OM reconstitutions using extracted material have given further support to this selective interaction. The incorporation of acetate extracted OMPs into reconstituted OM has indicated a possible iron transport function for one or more of these proteins. Calculations of Fe2+ :LPS molar binding ratios based on compositional data and these in vivo and in vitro studies show two forms of iron binding to the surface LPS, which may be applicable to the parameters at work in the natural environment of the bacteria

RT-PCR Analysis of Prn-p mRNA Expression in Normal and Scrapie-Infected B6.1(Prn-pb) . B6(Prn-pa). B6xB6.1(Prn-pa^b) , Tgl5 (Prn-p2a/3b) and Prn-pablated Mice

Brains and spleens were extracted from B6.I, B6, FI, Tgl5, and ablated strains of mice, both normal and scrapieinfected. Each strain exhibits a different incubation time due to slight differences found in the allele coding for Prnp mRNA. Total RNA was isolated from these organs. Absorbance readings at 260 nm and 280 nm were used to calculate the concentration of total RNA for each tissue. The reverse transcriptase polymerase chain reaction (RTPCR) was then used to identify different Prn-p alleles and to determine if a quantitative difference in Prn-p mRNA expression exists in the aforementioned mouse strains. Successful distinction and amplification of several Prnp mRNA alleles using RT-PCR has laid the groundwork for subsequent quantitative analyses of Prn-p mRNA

TPR-CONTAINING PROTEINS CONTROL PROTEIN ORGANIZATION AND HOMEOSTASIS FOR THE ENDOPLASMIC RETICULUM

The endoplasmic reticulum (ER) is a complex, multifunctional organelle comprised of a continuous membrane and lumen that is organized into several functional regions. It plays various roles including protein translocation, folding, quality control, secretion, calcium signaling, and lipid biogenesis. Cellular protein homeostasis is maintained by a complicated chaperone network, and the largest functional family within this network consists of proteins containing tetratricopeptide repeats (TPRs). TPRs are well-studied structural motifs that mediate intermolecular protein-protein interactions, supporting interactions with a wide range of ligands or substrates. Nine TPR-containing proteins have been shown to localize to the ER and control protein organization and homeostasis within this multifunctional organelle. Here, we discuss the roles of SEL1L, ERdj6, FICD, TMTC1-4, TTC13 and TTC17 and how they contribute to controlling ER processes and organization. The crucial roles that TPR-containing proteins play in the ER are highlighted by diseases or defects associated with their mutation or disruption

Thermochronology, landscape evolution and hydrogeology of the Katonga Valley in south west Uganda

The reversed river systems of south west Uganda attracted geoscientists to study the geomorphology of the region in the mid 20th century. During the succeeding fifty years the population and GDP per capita have both risen between five and six fold with a consequent increase in water demand. This thesis aims to apply modern quantitative techniques and theoretical developments to improve our understanding of the landscape evolution of the Katonga Valley and contribute to the groundwater resource assessment of associated alluvial deposits. Karoo-age glaciogenic strata were discovered filling the western valley. Subsequent apatite fission track analyses reveal that the currently exposed rocks were reheated to a temperature consistent with over 2 km of burial during the Mesozoic. Therefore, it is inferred that the western River Katonga has preferentially eroded a Gondwanan paleovalley exhumed from beneath the former sedimentary cover. Electrical resistivity tomography of the valley fill has identified three broad cycles of erosion and deposition, including: 1) The Gondwanan palaeovalley with indurated glaciogenic strata; 2) The Neogene relict valley with fluviolacustrine sediments; and, 3) The late Quaternary channel and with recent wetland deposits. Downwarping of the Victoria Basin in the east produced the first drainage divide on the originally westward flowing River Katonga during the middle Pleistocene. Downthrow of the George Basin in the west led to rejuvenation of the western landscape prior to the formation of a second drainage divide due to rift flank uplift. Sand and gravel associated with an old denuded landscape survives in terraces above the water table in the central valley. Variable climate and fluctuating lake levels led to the deposition of fluviolacustrine deposits in the eastern valley. Pumping tests in this silty sand indicate that the transmissivity is almost always adequate for village water use and is sometimes commensurate with town water supplies

Cow, farm, and herd management factors in the dry period associated with raised somatic cell counts in early lactation

This study investigated cow characteristics, farm facilities, and herd management strategies during the dry period to examine their joint influence on somatic cell counts (SCC) in early lactation. Data from 52 commercial dairy farms throughout England and Wales were collected over a 2-yr period. For the purpose of analysis, cows were separated into those housed for the dry period (6,419 cow-dry periods) and those at pasture (7,425 cow-dry periods). Bayesian multilevel models were specified with 2 response variables: ln SCC (continuous) and SCC >199,000 cells/mL (binary), both within 30 d of calving. Cow factors associated with an increased SCC after calving were parity, an SCC >199,000 cells/mL in the 60 d before drying off, increasing milk yield 0 to 30 d before drying off, and reduced DIM after calving at the time of SCC estimation. Herd management factors associated with an increased SCC after calving included procedures at drying off, aspects of bedding management, stocking density, and method of pasture grazing. Posterior predictions were used for model assessment, and these indicated that model fit was generally good. The research demonstrated that specific dry-period management strategies have an important influence on SCC in early lactation

fMRI-Compatible Registration of Jaw Movements Using a Fiber-Optic Bend Sensor

A functional magnetic resonance imaging (fMRI)-compatible fiber-optic bend sensor was investigated to assess whether the device could be used effectively to monitor opening and closing of the jaw during an fMRI experiment at 3 T. In contrast to surface electromyography, a bend sensor fixed to the chin of the participant is fast and easy to use and is not affected by strong electromagnetic fields. Bend sensor recordings are characterized by high validity (compared with concurrent video recordings of mouth opening) and high reliability (comparing two independent measurements). The results of this study indicate that a bend sensor is able to record the opening and closing of the jaw associated with different overt speech conditions (producing the utterances /a/, /pa/, /pataka/) and the opening of the mouth without speech production. Data post-processing such as filtering was not necessary. There are several potential applications for bend sensor recordings of speech-related jaw movements. First, bend sensor recordings are a valuable tool to assess behavioral performance, such as response latencies, accuracies, and completion times, which is particularly important in children, seniors, or patients with various neurological or psychiatric conditions. Second, the timing information provided by bend sensor data may improve the predicted hemodynamic response that is used for fMRI analysis based on the general linear model (GLM). Third, bend sensor recordings may be included in GLM analyses not for statistical contrast purposes, but as a covariate of no interest, accounting for part of the data variance to model fMRI artifacts due to motion outside the field of view

The Continuing Development of the Tort of Bad Faith in Montana

Bad Fait