污泥龄对活性污泥处理微量磺胺类药物的影响

为了研究污泥龄对活性污泥系统处理微量磺胺类药物（5 μg/L）的影响,共运行了4个试验室规模（3L）的序批式活性污泥反应器（SBR）,其污泥龄分别为2、8、14、20 d。批次摇瓶试验通过设置3个工况（正常运行,加入生物抑制剂,无微生物）来讨论在1个运行周期（8 h）中对浓度惟5 μg/L磺胺甲恶唑的吸附作用、生物降解作用和挥发损失。试验结果显示对磺胺甲恶唑的总去除量为2.14 ± 0.60 μg/g SS,吸附作用占总去除量的63%;磺胺嘧啶为1.14 ± 0.63 μg/g SS,83%;磺胺间二甲氧为2.33± 0.67 μg/g SS, 35%;磺胺甲基嘧啶为2.45 ± 0.85 μg/g SS,55%;磺胺类药物的去除效果与污泥的污泥龄有着非常显著的关系（p<0.02）。通过运行加入磺胺甲恶唑（进水5 μg/L)的反应器60 d,4个反应器对磺胺甲恶唑的平均去除率分别为10%、41%、51%、58%,处理效果随着污泥龄的增加而变好,同时单位污泥去除率随着污泥龄的增加而降低,SRT=2 d的反应器由于存在大量的丝状菌,使得单位污泥对磺胺甲恶唑去除率大大高于其他3个反应器。通过分子生物学分析,发现微生物群落结构的变化不大,从而说明了影响磺胺类药物处理效果的主要因素在于更强的吸附能力,更高的污泥浓度。     

A mutation in the conserved helix termination peptide of keratin 5 in hereditary skin blistering.

In the hereditary blistering condition epidermolysis bullosa simplex, the skin blisters on trauma following rupture of epidermal basal cells. Clinical variations range from severely incapacitating, especially in early childhood, to mild forms that may not even present clinically. Dowling-Meara epidermolysis bullosa simplex is characterized by clusters of epidermal blisters and keratin clumping in the cytoplasm; recent reports describe potentially causal mutations in keratin 14 (refs 2, 3). Here we describe a 'complementary' mutation at the other end of the other keratin expressed by these cells (K5, coexpressed with K14), a change from a Glu to a Gly in the helix termination peptide, detected by altered antibody binding and confirmed by sequencing using the polymerase chain reaction. The two conserved helix boundary peptides are predicted to be essential for filament assembly, and the requirement for two complementary (type I and type II) keratins is absolute. Epidermolysis bullosa simplex diseases demonstrate the function of the keratin cytoskeleton in resisting compaction stresses which otherwise lead to cell lysis.     

Mass spectrometry-based proteomics in the life sciences

Over the last 20 years, mass spectrometrybased proteomics has become an indispensable tool in the cellular and molecular life sciences. This has been enabled by the soft ionisation techniques of electrospray and matrix-assisted laser desorption-ionisation, which allow the gentle ionisation and vaporisation of large, thermally labile biomolecules. Innovative instrumentation designs and biochemical strategies have brought success in the large-scale identification and quantification of proteins, as well as the characterisation of their complexes and post-translational modifications. This review describes the instrumentation used for proteomics research. It presents an overview of the current applications of mass spectrometry-based proteomics to the cellular and molecular life sciences, and discusses challenges that exist for research in the future.Received 7 January 2005; accepted 27 January 2005     

From Teaching to Learning: Technological Potential and Sustainable, Supported Open Learning

The central theme of this paper is the current interest in most educational institutions in moving from teaching to learning as their main system model and the implications which technology media have for unravelling the debate and influencing the resulting practice (for example see Active Learning: Using the Internet for Teaching, Number 2, July, 1995), Our chosen strategy for dealing with the central theme is to consider how we use language, metaphor and models to describe systems for teaching and learning and what is the role of technology in these systems. In particular we describe how the Open University is moving from an analysis of individual technologies to a synthesis of the educational ideas into a sustainable system that conforms to the University's policy of supported open learning. This includes focusing on open and equal access to courses, considerable attention to staff development and training (specifically in core teaching areas such as face to face tuition, correspondence tuition, student support, telephone and other media supported communication) as well as the necessity and value of reflection on practice (e.g. see Baker, Tomlinson et al,, 1996). In this first section, taking as our starting point the traditional linear view of educational structures, we build upon the notion of the learning system and describe this as an approach with a somewhat long and surprising history originating in the Socratic method. An eductive, cyclic learning model is introduced, and the historical impact of technology on this model is briefly reviewed in a global context by addressing the specific issue of access from the developing countries. Following from this, in sections two and three two types of teaching are described, under the labels of conventional and distance. It is argued that each has strengths and tendencies towards the eductive learning system introduced in section one. However, it is also argued that each has flaws which provide problems for the development of a learning system which can be sustained at distance. An analysis based upon metaphor is applied. In section four, it is then argued that in the conventional model there is a system with excellent learning potential but with an organisational structure which often does not encourage it whereas in the distance model there is the potential organisation for providing feedback but often little effective use made of it. That lack of use includes the new technologies which are now being focused on by the Open University, both in terms of the INSTILL initiative (Integrate New Systems and Technologies Into Lifelong Learning) and the Technology Strategy for Academic Advantage (Laurillard, Christmas et al., 1996). These technologies are argued, in section five, to be capable of being tactically effective in stimulating and supporting the strategic aim of learning. Technology mediation is discussed both in terms of course-based teaching and in terms of research opportunities. In section six a range of problem/opportunity areas of immediate concern for the extension of this technologically mediated system to the developing countries are discussed, while policy implications for the extension of supported open learning are drawn out in section seven. These include policies toward co-learning, access to learning, quality standards and the authorship of educational material.     

Identification of self peptides bound to purified HLA-B27

A pool of endogenous peptides bound to the human class I MHC molecule, HLA-B27, has been isolated. Microsequence analysis of the pool and of 11 HPLC-purified peptides provides information on the binding specificity of the HLA-B27 molecule. The peptides all seem to be nonamers, seven of which match to protein sequences in a database search. These self peptides derive from abundant cytosolic or nuclear proteins, such as histone, ribosomal proteins, and members of the 90K heat-shock protein family.