The exosome and human ribosome biogenesis

Exoribonucleases have many important functions in the cell including RNA processing, turnover and quality control. One of the key 3’-5’ exonucleases is the exosome, a multiprotein complex that has been extensively characterised in yeast. Many substrates that undergo maturation and/or degradation involving the yeast exosome have been identified and these include tRNAs, mRNAs, snRNAs, snoRNAs and rRNAs. By comparison, the human exosome is poorly understood and it is not clear whether functions of the yeast exosome are conserved in higher eukaryotes. We show that the human exosome has degradation functions including the turnover, but not the processing, of snoRNAs and the recycling of excised pre-rRNA fragments. We and others have shown that the human exosome also participates in pre-rRNA processing to form the mature 3’ end of 5.8S rRNA. Here we identify a novel role for the exosome in the processing of the pre-rRNA internal transcribed spacer 1 (ITS1). The small (18S) and large (5.8S and 28S) subunit rRNAs are co-transcribed as a single precursor. Processing of ITS1 is a key step in ribosome biogenesis as it separates 18S from the large subunit rRNAs and in higher eukaryotes it involves an additional processing step compared to yeast. We define alternative ITS1 processing pathways in human cells. In the major pathway, following an endonucleolytic cleavage to separate the small and large subunit rRNAs, the exosome, which is not involved in ITS1 processing in yeast, processes to within 25 nucleotides of the 3’ end of 18S. Our data highlight significant differences between the nucleases involved in ITS1 processing in yeast and humans. However, it appears that the roles of several yeast biogenesis factors are conserved in higher eukaryotes. Further, we have investigated mechanisms by which exonucleolytic processing of ITS1 may be regulated and suggest how this could be coordinated with the final maturation steps of the pre-40S complex.EThOS - Electronic Theses Online ServiceBBSRCWellcome TrustGBUnited Kingdo

The design of novel microwave-heated reaction cells for infrared spectroscopy

Two novel microreactor cells for the investigation of catalysts by in-situ infrared spectroscopy under microwave and conventional heating are presented. A transmission infrared microreactor cell is demonstrated which holds a pressed catalyst disc in a controlled atmosphere and allows study of reactions from ambient temperatures to over 473 K. A cell that allows diffuse reflectance spectroscopy under reaction conditions up to 373 K under microwave heating and 423 K under conventional heating is also described. The optical characteristics of these cells are determined by the choice of CaF2 as the window material, allowing transmission from 77000-1110 cm−1. An oscillating microwave power heating regime was used to study the oxidation of carbon monoxide in air over the supported platinum catalysts EUROPT-1 and EUROPT-3, and their support oxides in these cells. The reaction was followed by time-resolved infrared spectroscopy and mass spectrometry. Both displayed a number of features that oscillated with the same frequency as the microwave perturbation. Production of CO2 appeared to vary with temperature in the same manner whether the catalysts were heated conventionally or with microwave radiation. Although no specific microwave effect for this reaction was observed, accurate thermometry within the cells was limited through the constraints imposed by microwave heating. Preliminary infrared emission and liquid phase experiments using the transmission cell are also reported.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Assessment of total soil and plant trace elements in rice-based production systems in NE Italy

Recently, the widespread interest on soil enzymes is due to the need to develop sensitive indicators of soil quality that reflect the effects of land management on soil and assist land managers in promoting long-term sustainability of terrestrial ecosystems. The activities of six important enzymes involved in C, N, P, and S cycling were investigated in a paddy soil from the Veneto region, Italy, in four different rotation systems (rice-rice-rice, soya-rice-rice, fallow-rice and pea-soya-rice) with three replications in April (after field preparation, field moist condition), June (after seedling, waterlogged soil condition), August (after tillering stage of rice, waterlogged soil condition) and October (after rice harvesting, drained soil condition) over the 2012 growing season. Our results demonstrated that soil enzyme activities varied with rotation systems and growth stages in paddy field. Compared with field moist soil, drained soil condition resulted in a significant increase (P < 0.05) of β-glucosidase, arylsulfatase, alkaline and acid phosphatases, leucine aminopeptidase (except of F-R), and chitinase activities in all rotations, while compared with drained soil, waterlogging (in month of June, the early period of waterlogging) significantly decreased (P<0.05) β-glucosidase, alkaline and acid phosphatases, leucine aminopeptidase (except of P-S-R), arylsulfatase, chitinases. Soil organic-C was positively correlated with acid and alkaline phosphatases, and arylsulfatase while ß-glucosidase, chitinases and leucine aminopeptidase were not significantly correlated to soil organic-C. Enzyme activities were always correlated among them

Assessment of total soil and plant elements in rice-based production systems in NE Italy

Macro- and micronutrients concentrations and PTEs contents in soils and plants (rice) fromthe rice district in the Venetian territory (NE Italy) have been determined by Inductive Coupled Plasma Optical Emission Spectrometry (ICP-OES), with the following aims: - to determine the background levels of macro- and microelements in the study area; - to assess possible contamination of soils and plants; - to calculate the Translocation Factor (TF) of metals from soil to plant, and the possible hazard for human health. Four rice plots with different rotation systems were investigated from seedling time to harvesting; sampling of soils (0–30 cm) and plants was carried out 4 times during growing season (three replicates). Rice plants were separated into the roots, stems, leaves and grains, and then oven-dried. Chemical and physical analyses were carried out at the Soil Science Lab of the University of Bologna and Venice, respectively. The results obtained point to a land with high soil contamination by Li and TI. The total concentrations of most studied metals (Al, As, Be, Cd, Co, Cr, Cu, Fe, Ni, Pb, Sb, Sn, Sr, V, Zn) in the soil samples fell in the natural geochemical background concentration levels, even though the concentration levels of some of them (e.g. Sn) overcame the Italian threshold limits for green areas (DM 152/2006). Most elements are likely associated with the geochemistry of the parent material. Antimony and Ti contents in soils are positively correlated with soil pH, while As, Be, Fe, Li, Sb, Ti, Tl and Zn are negatively correlated with organic matter content. With the exception of strontium, soil metals are always correlated between variable couples. Heavy metals in plants vary according to the sampling season, texture and moisture, and soil pH. Most non-essential trace elements are accumulated in rice roots and, only in cases of essential micronutrients, in leaves. Therefore, rice can be assumed as an excluder plant (i.e. metal in the roots b metal in soil) for Li, Sn, Tl. The results of multiple linear regression analysis showed that soil extractable P and total Ca played an important role in predicting annual grain yield of rice. The average translocation of metals from the soil to the root was found to be N1, irrespective of the essential/not essential function; conversely, only essential elements (Cu, Fe, Mn, Zn) are translocated rather easily from the roots to leaves (TF ≤ 1) via xylem, and very little are translocated to grains (TF ≪1). Rice plants were able to accumulate non essential metals in their tissues especially in the roots, but not in the edible part, and this could be useful for the restoration of contaminated sites with a very limited hazard for human population consuming rice crops

Assessment of total soil and plant trace elements in rice-based production systems in NE Italy

Recently, the widespread interest on soil enzymes is due to the need to develop sensitive indicators of soil quality that reflect the effects of land management on soil and assist land managers in promoting long-term sustainability of terrestrial ecosystems. The activities of six important enzymes involved in C, N, P, and S cycling were investigated in a paddy soil from the Veneto region, Italy, in four different rotation systems (rice-rice-rice, soya-rice-rice, fallow-rice and pea-soya-rice) with three replications in April (after field preparation, field moist condition), June (after seedling, waterlogged soil condition), August (after tillering stage of rice, waterlogged soil condition) and October (after rice harvesting, drained soil condition) over the 2012 growing season. Our results demonstrated that soil enzyme activities varied with rotation systems and growth stages in paddy field. Compared with field moist soil, drained soil condition resulted in a significant increase (P < 0.05) of β-glucosidase, arylsulfatase, alkaline and acid phosphatases, leucine aminopeptidase (except of F-R), and chitinase activities in all rotations, while compared with drained soil, waterlogging (in month of June, the early period of waterlogging) significantly decreased (P<0.05) β-glucosidase, alkaline and acid phosphatases, leucine aminopeptidase (except of P-S-R), arylsulfatase, chitinases. Soil organic-C was positively correlated with acid and alkaline phosphatases, and arylsulfatase while ß-glucosidase, chitinases and leucine aminopeptidase were not significantly correlated to soil organic-C. Enzyme activities were always correlated among them

Process of psychological adjustment to multiple sclerosis : comparing the roles of appraisals, acceptance, and cognitive fusion

Background: Research in psychological adjustment to multiple sclerosis (MS) suggests that the way individuals appraise their condition can have an impact upon their psychological well-being and adjustment to their condition. Such research has influenced the development of Cognitive Behavioural Therapy (CBT) interventions in this population. In recent years, Acceptance and Commitment Therapy (ACT) has gathered increasing interest in relation to chronic health conditions. ACT does not target the content of thought, but rather focuses on the contexts in which thought occurs (i.e. how individuals relate to their experiences). Aim and Primary Hypothesis: A cross sectional design was used to compare the extent to which cognitive appraisals and ACT constructs (‘acceptance’ and ‘cognitive fusion’), mediate the relationship between physical symptoms of MS and psychological adjustment outcomes. It was hypothesised that in comparison to cognitive appraisals, ACT constructs would serve as stronger mediators of the relationship between physical symptoms of MS and outcome measures. This study also piloted a newly adapted measure of MS related acceptance, the Multiple Sclerosis Acceptance Questionnaire (MSAQ). Method and Results: Participants (N = 133) completed self-report measures of: MS symptom severity, various cognitive constructs (cognitive appraisals and ACT constructs), symptoms of psychological distress, and satisfaction with life. Multiple mediation analysis was then used to compare competing mediational hypotheses. In comparison to all measures of cognitive appraisals, the ACT constructs tended to be stronger mediators of the relationship between symptoms and outcome measures (both psychological distress, and satisfaction with life). There was also some evidence for appraisals of personal control mediating the relationship between symptoms of MS and psychological distress. Conclusions: This research suggests that ACT constructs may be relevant to the process of psychological adjustment to MS, and that ACT based interventions may be worthy of investigation in this population. The newly adapted MSAQ also shows preliminary promise as a measure of MS related acceptance.EThOS - Electronic Theses Online ServiceGBUnited Kingdo