Seneca’s Natural Questions: Platonism, Physics, and Stoic Therapy in the First Century AD

The combination of ethics and physics in Seneca’s Natural Questions has frequently puzzled scholars. Although a number of studies have attempted to reconcile the work’s ethical and physical parts, others maintain that there is no substantial connection between them. Both positions are problematic. The former glosses over the quite obvious ways in which these vivid accounts of vice are thematically at odds with the physics; the latter results in a bifurcation of the aims of the work. This study argues that the incongruous character of these passages plays an integral part in the work’s overall goal: to defend the Stoic account of the ‘the good’. This account was under attack from Platonist rivals. The Stoics argue that the good is grounded ultimately in the wellbeing of the cosmos as a whole; Platonists maintain that conceptualising the good as such is impossible because, as empiricists, the Stoics can only account for a subjective understanding of the good, grounded first and foremost in the wellbeing of the body. Seneca’s engagement with this debate is indicated by the frequent allusions to Plato in the work, particularly the idea of ‘separating soul from body’. Seneca suggests that a carefully structured study of nature can achieve this ‘separation’. This process helps agents to overcome the subjective, body-focussed perspective that the Platonists associate with empiricism. Seneca thus demonstrates a therapeutic means through which an empiricist agent could come to conceive of the good as the Stoics envisage it. This same process of separation from one’s body, however, also provides an ideal opportunity to reflect critically on the objects that we tend to misidentify as goods. It is here that the moralising passages prove useful. These arresting accounts of vice serve to jar us into critical reflection on where we ground our understanding of the good

Quercetin elevates p27Kip1 and arrests both primary and HPV16 E6/E7 transformed human keratinocytes in G1

Our previous work with primary bovine fibroblasts demonstrated that quercetin, a potent mutagen found in high levels in bracken fern (Pteridium aquilinum), arrested cells in G1 and G2/M, in correlation with p53 activation. The expression of bovine papillomavirus type 4 (BPV-4) E7 overcame this arrest and lead to the development of tumorigenic cells lines (Beniston et al., 2001). Given the possible link between papillomavirus infection, bracken fern in the diet and cancer of the upper gastrointestinal (GI) tract in humans, we investigated whether a similar situation would occur in human cells transformed by human papillomavirus type 16 (HPV-16) oncoproteins. Quercetin arrested primary human foreskin keratinocytes in G1. Arrest was linked to an elevation of the cyclin-dependent kinase inhibitor (cdki) p27Kip1. Expression of the HPV16 E6 and E7 oncoproteins in transformed cells failed to abrogate cell cycle arrest. G1 arrest in the transformed cells was also linked to an increase of p27Kip1 with a concomitant reduction of cyclin E-associated kinase activity. This elevation of p27Kip1 was due not only to increased protein half-life, but also to increased mRNA transcription

An Investigation Into the Synergism Between Bovine Papillomavirus Type 4 and the Flavonoid Quercetin in the Transformation of Primary Bovine Palate Fibroblasts

Bovine papillomavirus type 4 (BPV 4) infects the upper alimentary canal of cattle causing benign papillomas which can progress to squamous carcinomas in cattle grazing on bracken fern (BF). A single treatment with quercetin, a well characterised and potent mutagen found in BF, can cause full oncogenic transformation of cells partially transformed by BPV-4. Quercetin elevates the activity of the BPV-4 enhancer/promoter element (LCR) by up to four fold but this cannot fully explain the observed effect as the timing of quercetin exposure is critical for full transformation of the cells. We show that quercetin exposure arrests normal PalF cells in the G1 phase of the cell cycle, and this G1 arrest correlates with an increase in p53 protein levels and transcriptional activity. Cells transformed by expression of either BPV 4 E7 and Ha-ras or the BPV4 genome and Ha-ras, fail to arrest in G1 after subsequent quercetin treatments. In these cells which are transformed but non-tumorigenic, p53 protein is elevated and transcriptionally activated in response to quercetin exposure. Yet the lack of cell cycle arrest is probably due to the viral protein E7 inhibiting p2Waf1/Cip1. In the transformed tumorigenic cells the failure to arrest in the G1 phase of the cell cycle is also evident. p53 protein is still present and even its stabilisation in response to quercetin can be observed in some cell lines, however p53 transcriptional activity is inhibited, probably as a result of p53 mutation. Additionally the protein which mediates p53 dependent cell cycle arrest, p2Waf1/Cip1 is also absent from all the tumorigenic cells lending further evidence to the loss of p53 as a transcriptional activator. Here we propose a model in which in normal cells quercetin induces G1 arrest, mediated by p53. Abrogation of this arrest by BPV-4 E7 allows the cell to proliferate allowing the accumulation of inheritable damage, including mutations of the p53 gene at later stages. The net effect of this is full tumorigenic transformation of the cell

Towards an automated analysis of bacterial peptidoglycan structure.

Peptidoglycan (PG) is an essential component of the bacterial cell envelope. This macromolecule consists of glycan chains alternating N-acetylglucosamine and N-acetylmuramic acid, cross-linked by short peptides containing nonstandard amino acids. Structural analysis of PG usually involves enzymatic digestion of glycan strands and separation of disaccharide peptides by reversed-phase HPLC followed by collection of individual peaks for MALDI-TOF and/or tandem mass spectrometry. Here, we report a novel strategy using shotgun proteomics techniques for a systematic and unbiased structural analysis of PG using high-resolution mass spectrometry and automated analysis of HCD and ETD fragmentation spectra with the Byonic software. Using the PG of the nosocomial pathogen Clostridium difficile as a proof of concept, we show that this high-throughput approach allows the identification of all PG monomers and dimers previously described, leaving only disambiguation of 3-3 and 4-3 cross-linking as a manual step. Our analysis confirms previous findings that C. difficile peptidoglycans include mainly deacetylated N-acetylglucosamine residues and 3-3 cross-links. The analysis also revealed a number of low abundance muropeptides with peptide sequences not previously reported. Graphical Abstract The bacterial cell envelope includes plasma membrane, peptidoglycan, and surface layer. Peptidoglycan is unique to bacteria and the target of the most important antibiotics; here it is analyzed by mass spectrometry

Innovation development – an action learning programme for medical scientists and engineers

© 2014, © 2014 Taylor & Francis. There is increasing evidence that action learning is valuable in a higher education setting. This paper goes on to report a personal development programme, based on principles of critical action learning, where the aim is to equip early-career scientists and engineers working in a university setting with the knowledge, skills and confidence to approach the management of innovation. After learning about action learning and critical reflection, the participants, all postdoctorate researchers, completed innovation projects at work, meeting in action learning sets as they proceed. We explain a method of critical thinking before reporting results from an evaluation study based on interviews and focus groups. We consider examples of projects undertaken before considering challenges for students with this approach to learning. Challenges included scepticism about the usefulness of management literature, difficulties in finding ‘problems’ within the constraints of postdoctoral work, and the discomfort and intensiveness of action learning. However, through adaptation by the tutors with students, some significant results were achieved

klf2ash317 Mutant Zebrafish Do Not Recapitulate Morpholino-Induced Vascular and Haematopoietic Phenotypes.

INTRODUCTION AND OBJECTIVES: The zinc-finger transcription factor Krϋppel-like factor 2 (KLF2) transduces blood flow into molecular signals responsible for a wide range of responses within the vasculature. KLF2 maintains a healthy, quiescent endothelial phenotype. Previous studies report a range of phenotypes following morpholino antisense oligonucleotide-induced klf2a knockdown in zebrafish. Targeted genome editing is an increasingly applied method for functional assessment of candidate genes. We therefore generated a stable klf2a mutant zebrafish and characterised its cardiovascular and haematopoietic development. METHODS AND RESULTS: Using Transcription Activator-Like Effector Nucleases (TALEN) we generated a klf2a mutant (klf2ash317) with a 14bp deletion leading to a premature stop codon in exon 2. Western blotting confirmed loss of wild type Klf2a protein and the presence of a truncated protein in klf2ash317 mutants. Homozygous klf2ash317 mutants exhibit no defects in vascular patterning, survive to adulthood and are fertile, without displaying previously described morphant phenotypes such as high-output cardiac failure, reduced haematopoetic stem cell (HSC) development or impaired formation of the 5th accessory aortic arch. Homozygous klf2ash317 mutation did not reduce angiogenesis in zebrafish with homozygous mutations in von Hippel Lindau (vhl), a form of angiogenesis that is dependent on blood flow. We examined expression of three klf family members in wildtype and klf2ash317 zebrafish. We detected vascular expression of klf2b (but not klf4a or biklf/klf4b/klf17) in wildtypes but found no differences in expression that might account for the lack of phenotype in klf2ash317 mutants. klf2b morpholino knockdown did not affect heart rate or impair formation of the 5th accessory aortic arch in either wildtypes or klf2ash317 mutants. CONCLUSIONS: The klf2ash317 mutation produces a truncated Klf2a protein but, unlike morpholino induced klf2a knockdown, does not affect cardiovascular development

The potential impacts of climate change on Europe

GCMs project higher temperatures for all of Europe, with greater changes at higher latitudes. In Northern and Western Europe, winter precipitation may increase, and summer precipitation may remain unchanged. Different models show different changes for Southern, Central and Eastern Europe. Water resources follow roughly the same patterns, although higher temperatures increase the risk of summer droughts, particularly in Southern and Central Europe. In Western Europe, river floods may increase. Vegetation patterns may drastically change, with some species and communities expanding and other shrinking. Particularly vulnerable are ecosystems depending on northern cold, and ecosystems isolated by geography or human activity. On the whole, agriculture would seem to benefit from climatic change, although not-well-understood pests and water availability may alter this. Sea level rise would negatively affect low-lying coasts and deltas, which support important natural and human systems. In a warmer climate, cold-related health problems would decline, but heat-related ones would increase. Tentatively, the balance is reduced mortality. Less important climate-related diseases would, on balance, increase. Research on other sector has progressed less far; results show mixed positive and negative impacts. Expressing all impact in money and adding up suggests a light negative overall impact of climate change on Europe

Wind speed measurements and forest damage in Canton Zurich (Central Europe) from 1891 to winter 2007

The most severe damage to forests in central Europe occurs during winter storms that are caused by Northern Hemispheric mid-latitude cyclones. These winter storms have caused several catastrophic windthrows during the past four decades. Amounts of forest storm damage are believed to be a function of both the size of the forest and the storm intensity. To test this hypothesis, the Zurich region (city and canton) was chosen because long-term climate observation data is available for the region. The relationships between forest attributes, wind speed and forest damage were explored by comparing data on forests and wind speed from 107 winters with forest damage. Storm damage was defined as the proportion of damaged forests with respect to the growing stock. The variables: daily wind run (91 years), daily maximum hourly average wind speed (107 years) and peak gust wind speed (74 years) were homogenized with respect to high wind speed and related to levels of forest damage. High maximum wind speed at the end of the 19th century and at the beginning of the 20th century was followed by low maximum wind speed in the 1940s, 1960s and 1970s. Since then, maximum values have increased. Gusts (extremes of the maximum wind speed) increased from the beginning of the recordings in 1933 and peaked in the early 1990s. Forest damage due to winter storms is best correlated with peak wind speed. Gusts exceeding 40 m/s and resulting in catastrophic windthrow have increased in recent winters

Hyphal growth in Candida albicans requires the phosphorylation of Sec2 by the Cdc28-Ccn1/Hgc1 kinase

This study establishes that Sec2, the guanine exchange factor (GEF) of the Rab GTPase Sec4, which has a central function in polarized exocytosis, undergoes CDK-dependent phosphorylation/relocalization in response to hypha-inducing signals