Transcription regulation of the Escherichia coli pcnB gene coding for poly(A) polymerase I: roles of ppGpp, DksA and sigma factors

Poly(A) polymerase I (PAP I), encoded by the pcnB gene, is a major enzyme responsible for RNA polyadenylation in Escherichia coli, a process involved in the global control of gene expression in this bacterium through influencing the rate of transcript degradation. Recent studies have suggested a complicated regulation of pcnB expression, including a complex promoter region, a control at the level of translation initiation and dependence on bacterial growth rate. In this report, studies on transcription regulation of the pcnB gene are described. Results of in vivo and in vitro experiments indicated that (a) there are three σ70-dependent (p1, pB, and p2) and two σS-dependent (pS1 and pS2) promoters of the pcnB gene, (b) guanosine tetraphosphate (ppGpp) and DksA directly inhibit transcription from pB, pS1 and pS2, and (c) pB activity is drastically impaired at the stationary phase of growth. These results indicate that regulation of the pcnB gene transcription is a complex process, which involves several factors acting to ensure precise control of PAP I production. Moreover, inhibition of activities of pS1 and pS2 by ppGpp and DksA suggests that regulation of transcription from promoters requiring alternative σ factors by these effectors of the stringent response might occur according to both passive and active models

The topographic evolution of the Tibetan Region as revealed by palaeontology

The Tibetan Plateau was built through a succession of Gondwanan terranes colliding with Asia during the Mesozoic. These accretions produced a complex Paleogene topography of several predominantly east–west trending mountain ranges separated by deep valleys. Despite this piecemeal assembly and resultant complex relief, Tibet has traditionally been thought of as a coherent entity rising as one unit. This has led to the widely used phrase ‘the uplift of the Tibetan Plateau’, which is a false concept borne of simplistic modelling and confounds understanding the complex interactions between topography climate and biodiversity. Here, using the rich palaeontological record of the Tibetan region, we review what is known about the past topography of the Tibetan region using a combination of quantitative isotope and fossil palaeoaltimetric proxies, and present a new synthesis of the orography of Tibet throughout the Paleogene. We show why ‘the uplift of the Tibetan Plateau’ never occurred, and quantify a new pattern of topographic and landscape evolution that contributed to the development of today’s extraordinary Asian biodiversity

The sequence of the distal end of the E. coli ribosomal RNA rrnE operon indicates conserved features are shared by rrn operons.

The 1440 nucleotides of the distal region of the E. coli ribosomal RNA operon found on the lambda aroE transducing phage has been sequenced. We show that the lambda aroE hybrid rrn operon ends after a solitary 5S RNA gene with rrnE distal sequence. A single terminator structure of dyad symmetry followed by a run of six T's have been identified and compared to other sequenced rrn terminator hairpins. Immediately adjacent to the hairpin is a region of interrupted but conserved sequence that is shared by rrnE, rrnB and rrnD. An open reading frame of 127 amino acids abuts the terminator structure. Another open reading frame of 147 amino acids is found on the opposite strand several hundred nucleotides downstream

Die Umgestaltung des Praktischen Jahres im Modellstudiengang MaReCuM an der Medizinischen Fakultät Mannheim: das Quartal Ambulante Medizin

Introduction: To reflect the ever-growing importance of outpatient care in medical education, MaReCuM - a reformed curriculum, also referred to as a model study programme - was introduced at the Medical Faculty Mannheim in 2006. It divided the final year of medical study into quarters and added a mandatory quarter dedicated to ambulatory medicine. This project report presents our experiences, the costs and the evaluation results connected with making specific changes to the final year of undergraduate medical study.Project description: The final-year quarter in ambulatory medicine, taught at the Medical Faculty's outpatient teaching placements, allows final-year medical students to gather practical experience in one of four elective areas in outpatient care. The parallel coursework encompasses interactive case presentations and practical reviews. Relevant curricular content on ambulatory medicine is then tested in the oral/practical section of the M3 medical examination.Results: Students are very satisfied with the academic quality of the final-year quarter in ambulatory medicine. Restructuring the final year, generating the concept and recruiting teaching placements at outpatient facilities required additional full-time positions in the beginning.Discussion: The processes of reforming MaReCuM have not only contributed to a stronger recognition of ambulatory medicine in the final year and in the clinical phase of study, but have also enabled broader opportunities for focussing individual choices during medical education. A high caliber of academics in the quarter in ambulatory medicine can be achieved with a calculable amount of organisational effort.Conclusion: Anchoring a curriculum on ambulatory medicine in medical education is possible through restructuring the final year and is received positively by students. The success of MaReCuM demonstrates the feasibility of the recommendations made by the German Council of Science and Humanities (Wissenschaftsrat).Einleitung: Um den steigenden Stellenwert der ambulanten Patientenversorgung in der medizinischen Ausbildung abzubilden, wurde an der Medizinischen Fakultät Mannheim im Jahr 2006 ein Modellstudiengang eingeführt, dessen Kern in der Quartalisierung des Praktischen Jahres (PJ) und der Einführung eines Wahlpflichtquartals Ambulante Medizin besteht. Unser Projektbericht stellt die Erfahrungen sowie die Kosten und die Evaluationsergebnisse der Umsetzung der Änderungen im Praktischen Jahr dar. Projektbeschreibung: Das PJ-Quartal Ambulante Medizin in ambulanten Lehreinrichtungen der Fakultät vermittelt PJ-Studierenden Praxiserfahrung in einem von vier wählbaren ambulanten Bereichen. Der begleitende Unterricht umfasst interaktive Fall-Referate und Praxis-Repetitorien. Die Inhalte des Quartals Ambulante Medizin werden im mündlich-praktischen Teil des M3-Examens geprüft.Ergebnisse: Die Studierenden sind mit der Qualität der Ausbildung im PJ-Quartal Ambulante Medizin sehr zufrieden. Die Umstrukturierung des PJ, die Erstellung des Konzepts und die Akquise der ambulanten Lehrplätze erforderte zumindest initial zusätzliche Vollkostenstellen.Diskussion: Die Reformprozesse im Modellstudiengang haben sowohl zu einer verstärkten Anerkennung der ambulanten Medizin im Praktischen Jahr und im klinischen Studium als auch zu einer erweiterten Neigungsorientierung im Studium beigetragen. Eine hohe Ausbildungsqualität im Quartal Ambulante Medizin kann mit einem kalkulierbaren organisatorischen Aufwand erreicht werden. Schlussfolgerung: Eine Verankerung ambulanter Inhalte im Medizinstudium ist durch eine Umgestaltung des PJ möglich und wird von den Studierenden positiv bewertet. Die erfolgreiche Anwendung des Modellstudiengangs belegt die Machbarkeit der Empfehlungen des Wissenschaftsrats