Cutting-edge Life Sciences in Swiss gymnasia - success is not a secret.

What can be done to achieve a high-quality education in Life Sciences at gymnasia level that arouses the interest of most students and motivates them to accomplish high performances? The recipe for success is simple: Employ excellent natural scientists who combine the passion for their subject with strong pedagogic skills as teachers to your school. The challenge is to create an environment that makes teaching attractive for scientists and that has a positive and lasting effect on the motivation of the teachers. We consider the following criteria especially significant: The social structure/arrangement is likely to be the key aspect. Ideally it consists of a constructive relation between the teachers, the school administrators, the staff and most importantly the students. The work must be challenging, but the workload should be in a good proportion to the resources of the teachers. To communicate a realistic impression of Life Sciences an adequate infrastructure and facilities are necessary that allow an education based on experiments and practical. The curriculum should consider the interests of the students and should contain topics which are relevant for society. Finally it should grant enough educational latitude for the teachers so they can use their specialized skills. Contacts to other gymnasia, universities and industry are important for orientation, the exchange of knowledge and to enable extracurricular projects.

Cordycepin-hypersensitive growth links elevated polyphosphate levels to inhibition of poly(A) polymerase in Saccharomyces cerevisiae.

To identify genes involved in poly(A) metabolism, we screened the yeast gene deletion collection for growth defects in the presence of cordycepin (3'-deoxyadenosine), a precursor to the RNA chain terminating ATP analog cordycepin triphosphate. Deltapho80 and Deltapho85 strains, which have a constitutively active phosphate-response pathway, were identified as cordycepin hypersensitive. We show that inorganic polyphosphate (poly P) accumulated in these strains and that poly P is a potent inhibitor of poly(A) polymerase activity in vitro. Binding analyses of poly P and yeast Pap1p revealed an interaction with a k(D) in the low nanomolar range. Poly P also bound mammalian poly(A) polymerase, however, with a 10-fold higher k(D) compared to yeast Pap1p. Genetic tests with double mutants of Deltapho80 and other genes involved in phosphate homeostasis and poly P accumulation suggest that poly P contributed to cordycepin hypersensitivity. Synergistic inhibition of mRNA synthesis through poly P-mediated inhibition of Pap1p and through cordycepin-mediated RNA chain termination may thus account for hypersensitive growth of Deltapho80 and Deltapho85 strains in the presence of the chain terminator. Consistent with this, a mutation in the 3'-end formation component rna14 was synthetic lethal in combination with Deltapho80. Based on these observations, we suggest that binding of poly P to poly(A) polymerase negatively regulates its activity.

Pho91 Is a vacuolar phosphate transporter that regulates phosphate and polyphosphate metabolism in Saccharomyces cerevisiae.

Inorganic polyphosphate (poly P) is a biopolymer that occurs in all organisms and cells and in many cellular compartments. It is involved in numerous biological phenomena and functions in cellular processes in all organisms. However, even the most fundamental aspects of poly P metabolism are largely unknown. In yeast, large amounts of poly P accumulate in the vacuole during growth. It is neither known how this poly P pool is synthesized nor how it is remobilized from the vacuole to replenish the cytosolic phosphate pool. Here, we report a systematic analysis of the yeast phosphate transporters and their function in poly P metabolism. By using poly P content as a read-out, it was possible to define novel functions of the five phosphate transporters: Pho84, Pho87, Pho89, Pho90, and Pho91, in budding yeast. Most notably, it was found that the low-affinity transporter Pho91 limits poly P accumulation in a strain lacking PHO85. This phenotype was not caused by a regulatory effect on the PHO pathway, but can be attributed to the unexpected localization of Pho91 in the vacuolar membrane. This finding is consistent with the hypothesis that Pho91 serves as a vacuolar phosphate transporter that exports phosphate from the vacuolar lumen to the cytosol.

Inorganic polyphosphate occurs in the cell wall of Chlamydomonas reinhardtii and accumulates during cytokinesis.

BACKGROUND: Inorganic polyphosphate (poly P), linear chains of phosphate residues linked by energy rich phosphoanhydride bonds, is found in every cell and organelle and is abundant in algae. Depending on its localization and concentration, poly P is involved in various biological functions. It serves, for example, as a phosphate store and buffer against alkali, is involved in energy metabolism and regulates the activity of enzymes. Bacteria defective in poly P synthesis are impaired in biofilm development, motility and pathogenicity. PolyP has also been found in fungal cell walls and bacterial envelopes, but has so far not been measured directly or stained specifically in the cell wall of any plant or alga. RESULTS: Here, we demonstrate the presence of poly P in the cell wall of Chlamydomonas reinhardtii by staining with specific poly P binding proteins. The specificity of the poly P signal was verified by various competition experiments, by staining with different poly P binding proteins and by correlation with biochemical quantification. Microscopical investigation at different time-points during growth revealed fluctuations of the poly P signal synchronous with the cell cycle: The poly P staining peaked during late cytokinesis and was independent of the high intracellular poly P content, which fluctuated only slightly during the cell cycle. CONCLUSION: The presented staining method provides a specific and sensitive tool for the study of poly P in the extracellular matrices of algae and could be used to describe the dynamic behaviour of cell wall poly P during the cell cycle. We assume that cell wall poly P and intracellular poly P are regulated by distinct mechanisms and it is suggested that cell wall bound poly P might have important protective functions against toxic compounds or pathogens during cytokinesis, when cells are more vulnerable.

Norming a Written Communication Rubric in a Graduate Health Science Course.

BACKGROUND: There is growing interest in the use of rubrics to assess written work. This study aimed to determine whether or not the norming of a written communication rubric improved scoring consistency among clinical faculty in a critical thinking course. The benefits of a formalized norming process are described. METHODS: Faculty-raters were trained to apply the rubric to a signature assignment while participating in calibration workshops. For each rubric criterion, faculty examined whether or not heightened congruence in scoring resulted from the training. Inter-rater reliability was determined after raters independently scored de-identified essays. RESULTS: Pre-workshop intra-class correlations (ICCs) were acceptable (i.e., >0.7) for three of five rubric criteria. Post-workshop ICCs for only two criteria were acceptable: disciplinary conventions, and sources and evidence. Rater attrition and lag-time between calibration and post-workshop activities likely contributed to reduced consistency. DISCUSSION: The rubric was useful for discriminating writing proficiency. Norming led to revision of the signature assignment, the rubric design, and a need for writing workshops. These changes will result in better student preparation for composing evidence-informed essays. Less-rigid approaches are worthy of future exploration.

Specific localization of inorganic polyphosphate (poly P) in fungal cell walls by selective extraction and immunohistochemistry.

Inorganic polyphosphate (poly P) is a linear polymer of phosphoanhydride-linked phosphate residues that occurs in all organisms and cells. It was found in all organelles and is particularly abundant in fungal vacuoles. The fungal cell wall also contains poly P, but very little is known about the nature and functions of poly P in this compartment. Here, we describe a novel method for the specific quantification and visualization of poly P in fungal cell walls. Selective extraction in high salt buffer revealed large poly P stores in cell walls of Mucorales and lower amounts in most other fungi tested. Staining with specific poly P binding proteins (PBPs) enabled the visualization of poly P in cell walls of selected species from all fungal phyla. The presence of an extracellular phosphate pool in the form of a strongly negatively charged polymer is suggested to have important functions as a phosphate source in mycorrhizal interactions, an antimicrobial compound or protection against toxicity of heavy metals.

Systematic screening of polyphosphate (poly P) levels in yeast mutant cells reveals strong interdependence with primary metabolism.

BACKGROUND: Inorganic polyphosphate (poly P) occurs universally in all organisms from bacteria to man. It functions, for example, as a phosphate and energy store, and is involved in the activation and regulation of proteins. Despite its ubiquitous occurrence and important functions, it is unclear how poly P is synthesized or how poly P metabolism is regulated in higher eukaryotes. This work describes a systematic analysis of poly P levels in yeast knockout strains mutated in almost every non-essential gene. RESULTS: After three consecutive screens, 255 genes (almost 4% of the yeast genome) were found to be involved in the maintenance of normal poly P content. Many of these genes encoded proteins functioning in the cytoplasm, the vacuole or in transport and transcription. Besides reduced poly P content, many strains also exhibited reduced total phosphate content, showed altered ATP and glycogen levels and were disturbed in the secretion of acid phosphatase. CONCLUSION: Cellular energy and phosphate homeostasis is suggested to result from the equilibrium between poly P, ATP and free phosphate within the cell. Poly P serves as a buffer for both ATP and free phosphate levels and is, therefore, the least essential and consequently most variable component in this network. However, strains with reduced poly P levels are not only affected in their ATP and phosphate content, but also in other components that depend on ATP or free phosphate content, such as glycogen or secreted phosphatase activity.

Novel method for the quantification of inorganic polyphosphate (iPoP) in Saccharomyces cerevisiae shows dependence of iPoP content on the growth phase.

Inorganic polyphosphate (iPoP)-linear chains of up to hundreds of phosphate residues-is ubiquitous in nature and appears to be involved in many different cellular processes. In Saccharomyces cerevisiae, iPoP has been detected in high concentrations, especially after transfer of phosphate-deprived cells to a high-phosphate medium. Here, the dynamics of iPoP synthesis in yeast as a function of the growth phase as well as glucose and phosphate availability have been investigated. To address this question, a simple, fast and novel method for the quantification of iPoP from yeast was developed. Both the iPoP content during growth and the iPoP "overplus" were highest towards the end of the exponential phase, when glucose became limiting. Accumulation of iPoP during growth required excess of free phosphate, while the iPoP "overplus" was only observed after the shift from low- to high-phosphate medium. The newly developed iPoP quantification method and the knowledge about the dynamics of iPoP content during growth made it possible to define specific growth conditions for the analysis of iPoP levels. These experimental procedures will be essential for the large-scale analysis of various mutant strains or the comparison of different growth conditions.