Introducing a new breed of wine yeast: interspecific hybridisation between a commercial Saccharomyces cerevisiae wine yeast and Saccharomyces mikatae

Interspecific hybrids are commonplace in agriculture and horticulture; bread wheat and grapefruit are but two examples. The benefits derived from interspecific hybridisation include the potential of generating advantageous transgressive phenotypes. This paper describes the generation of a new breed of wine yeast by interspecific hybridisation between a commercial Saccharomyces cerevisiae wine yeast strain and Saccharomyces mikatae, a species hitherto not associated with industrial fermentation environs. While commercially available wine yeast strains provide consistent and reliable fermentations, wines produced using single inocula are thought to lack the sensory complexity and rounded palate structure obtained from spontaneous fermentations. In contrast, interspecific yeast hybrids have the potential to deliver increased complexity to wine sensory properties and alternative wine styles through the formation of novel, and wider ranging, yeast volatile fermentation metabolite profiles, whilst maintaining the robustness of the wine yeast parent. Screening of newly generated hybrids from a cross between a S. cerevisiae wine yeast and S. mikatae (closely-related but ecologically distant members of the Saccharomyces sensu stricto clade), has identified progeny with robust fermentation properties and winemaking potential. Chemical analysis showed that, relative to the S. cerevisiae wine yeast parent, hybrids produced wines with different concentrations of volatile metabolites that are known to contribute to wine flavour and aroma, including flavour compounds associated with non-Saccharomyces species. The new S. cerevisiae x S. mikatae hybrids have the potential to produce complex wines akin to products of spontaneous fermentation while giving winemakers the safeguard of an inoculated ferment.Jennifer R. Bellon, Frank Schmid, Dimitra L. Capone, Barbara L. Dunn, Paul J. Chamber

A viscoelastic deadly fluid in carnivorous pitcher plants

Background : The carnivorous plants of the genus Nepenthes, widely distributed in the Asian tropics, rely mostly on nutrients derived from arthropods trapped in their pitcher-shaped leaves and digested by their enzymatic fluid. The genus exhibits a great diversity of prey and pitcher forms and its mechanism of trapping has long intrigued scientists. The slippery inner surfaces of the pitchers, which can be waxy or highly wettable, have so far been considered as the key trapping devices. However, the occurrence of species lacking such epidermal specializations but still effective at trapping insects suggests the possible implication of other mechanisms. Methodology/Principal Findings : Using a combination of insect bioassays, high-speed video and rheological measurements, we show that the digestive fluid of Nepenthes rafflesiana is highly viscoelastic and that this physical property is crucial for the retention of insects in its traps. Trapping efficiency is shown to remain strong even when the fluid is highly diluted by water, as long as the elastic relaxation time of the fluid is higher than the typical time scale of insect movements. Conclusions/Significance : This finding challenges the common classification of Nepenthes pitchers as simple passive traps and is of great adaptive significance for these tropical plants, which are often submitted to high rainfalls and variations in fluid concentration. The viscoelastic trap constitutes a cryptic but potentially widespread adaptation of Nepenthes species and could be a homologous trait shared through common ancestry with the sundew (Drosera) flypaper plants. Such large production of a highly viscoelastic biopolymer fluid in permanent pools is nevertheless unique in the plant kingdom and suggests novel applications for pest control

Microtubule dynamics in cell division : exploring living cells with polarized light microscopy

Author Posting. © The Author(s), 2008. This is the author's version of the work. It is posted here by permission of Annual Reviews for personal use, not for redistribution. The definitive version was published in Annual Review of Cell and Developmental Biology 24 (2008): 1-28, doi:10.1146/annurev.cellbio.24.110707.175323.This Perspective is an account of my early experience while I studied the dynamic organization and behavior of the mitotic spindle and its submicroscopic filaments using polarized light microscopy. The birefringence of spindle filaments in normally dividing plant and animal cells, and those treated by various agents, revealed: A) the reality of spindle fibers and fibrils in healthy living cells; B) the labile, dynamic nature of the molecular filaments making up the spindle fibers; C) the mode of fibrogenesis and action of orienting centers; and D) force-generating properties based on the disassembly and assembly of the fibrils. These studies, which were carried out directly on living cells using improved polarizing microscopes, in fact, predicted the reversible assembly properties of isolated microtubules

Why do patients want to have their blood tested? A qualitative study of patient expectations in general practice

BACKGROUND: General practitioners often take their impression of patients' expectations into account in their decision to have blood tests done. It is commonly recommended to involve patients in decision-making during consultations. The study aimed to obtain detailed information on patients' expectations about blood tests. METHODS: Qualitative study among patients in waiting rooms of general practices. Each patient was presented with a short questionnaire about their preferences in terms of diagnostics. Patients who would like blood tests to be done were interviewed. RESULTS: Fifty-seven (26%) of the 224 respondents wanted blood tests. Twenty-two were interviewed. Patients overestimated the qualities of blood tests. Favourable test results were regarded as proof of good health. Patients regarded blood tests as a useful instrument to screen for serious disorders, and were confirmed in this belief by people in their social environment and by the media. Many patients expected their GP to take an active test ordering approach, though some indicated that they might be convinced if their GP proposed a wait-and-see policy. CONCLUSIONS: GPs' perceptions about patient expectations seem justified: patients appear to have high hopes for testing as a diagnostic tool. They expect diagnostic certainty without mistakes and a proof of good health. The question is whether it would be desirable to remove patients' misconceptions, allowing them to participate in policy decisions on the basis of sound information, or whether it would be better to leave the misconceptions uncontested, in order to retain the 'magic' of additional tests and reassure patients. We expect that clarifying the precise nature of patients' expectations by the GP may be helpful in creating a diagnostic strategy that satisfies both patients and GPs. GPs will have to balance the benefits of reassuring their patients by means of blood tests which may be unnecessary against the benefits of avoiding unnecessary tests. Further research is needed into the effects of different types of patient information and the effects of testing on satisfaction and anxiety

Tongue lesions in psoriasis: a controlled study

BACKGROUND: Our objective was to study tongue lesions and their significance in psoriatic patients. METHODS: The oral mucosa was examined in 200 psoriatic patients presenting to Razi Hospital in Tehran, Iran, and 200 matched controls. RESULTS: Fissured tongue (FT) and benign migratory glossitis (BMG) were the two most frequent findings. FT was seen more frequently in psoriatic patients (n = 66, 33%) than the control group (n = 19, 9.5%) [odds ratio (OR): 4.69; 95% confidence interval (CI): 2.61–8.52] (p-value < 0.0001). BMG, too, was significantly more frequent in psoriatic patients (28 cases, 14%) than the control group (12 cases, 6%) (OR: 2.55; 95% CI: 1.20–5.50) (p-value < 0.012). In 11 patients (5.5%), FT and BMG coexisted. FT was more frequent in pustular psoriasis (7 cases, 53.8%) than erythemato-squamous types (56 cases, 30.4%). On the other hand, the frequency of BMG increased with the severity of psoriasis in plaque-type psoriasis assessed by psoriasis area and severity index (PASI) score. CONCLUSIONS: Nonspecific tongue lesions are frequently observed in psoriasis. Further studies are recommended to substantiate the clinical significance of these seemingly nonspecific findings in suspected psoriatic cases

Reprogramming of Escherichia coli K-12 Metabolism during the Initial Phase of Transition from an Anaerobic to a Micro-Aerobic Environment

Background: Many bacteria undergo transitions between environments with differing O2 availabilities as part of their natural lifestyles and during biotechnological processes. However, the dynamics of adaptation when bacteria experience changes in O2 availability are understudied. The model bacterium and facultative anaerobe Escherichia coli K-12 provides an ideal system for exploring this process. Methods and Findings: Time-resolved transcript profiles of E. coli K-12 during the initial phase of transition from anaerobic to micro-aerobic conditions revealed a reprogramming of gene expression consistent with a switch from fermentative to respiratory metabolism. The changes in transcript abundance were matched by changes in the abundances of selected central metabolic proteins. A probabilistic state space model was used to infer the activities of two key regulators, FNR (O2 sensing) and PdhR (pyruvate sensing). The model implied that both regulators were rapidly inactivated during the transition from an anaerobic to a micro-aerobic environment. Analysis of the external metabolome and protein levels suggested that the cultures transit through different physiological states during the process of adaptation, characterized by the rapid inactivation of pyruvate formate-lyase (PFL), a slower induction of pyruvate dehydrogenase complex (PDHC) activity and transient excretion of pyruvate, consistent with the predicted inactivation of PdhR and FNR. Conclusion: Perturbation of anaerobic steady-state cultures by introduction of a limited supply of O2 combined with time-resolved transcript, protein and metabolite profiling, and probabilistic modeling has revealed that pyruvate (sensed by PdhR) is a key metabolic signal in coordinating the reprogramming of E. coli K-12 gene expression by working alongside the O2 sensor FNR during transition from anaerobic to micro-aerobic conditions

Phenomenology and physical origin of shear-localization and shear-banding in complex fluids

We review and compare the phenomenological aspects and physical origin of shear-localization and shear-banding in various material types, namely emulsions, suspensions, colloids, granular materials and micellar systems. It appears that shear-banding, which must be distinguished from the simple effect of coexisting static-flowing regions in yield stress fluids, occurs in the form of a progressive evolution of the local viscosity towards two significantly different values in two adjoining regions of the fluids in which the stress takes slightly different values. This suggests that from a global point of view shear-banding in these systems has a common physical origin: two physical phenomena (for example, in colloids, destructuration due to flow and restructuration due to aging) are in competition and, depending on the flow conditions, one of them becomes dominant and makes the system evolve in a specific direction.Comment: The original publication is available at http://www.springerlink.co

CGRPα-Expressing Sensory Neurons Respond to Stimuli that Evoke Sensations of Pain and Itch

Calcitonin gene-related peptide (CGRPα, encoded by Calca) is a classic marker of nociceptive dorsal root ganglia (DRG) neurons. Despite years of research, it is unclear what stimuli these neurons detect in vitro or in vivo. To facilitate functional studies of these neurons, we genetically targeted an axonal tracer (farnesylated enhanced green fluorescent protein; GFP) and a LoxP-stopped cell ablation construct (human diphtheria toxin receptor; DTR) to the Calca locus. In culture, 10–50% (depending on ligand) of all CGRPα-GFP-positive (+) neurons responded to capsaicin, mustard oil, menthol, acidic pH, ATP, and pruritogens (histamine and chloroquine), suggesting a role for peptidergic neurons in detecting noxious stimuli and itch. In contrast, few (2.2±1.3%) CGRPα-GFP+ neurons responded to the TRPM8-selective cooling agent icilin. In adult mice, CGRPα-GFP+ cell bodies were located in the DRG, spinal cord (motor neurons and dorsal horn neurons), brain and thyroid—reproducibly marking all cell types known to express Calca. Half of all CGRPα-GFP+ DRG neurons expressed TRPV1, ∼25% expressed neurofilament-200, <10% contained nonpeptidergic markers (IB4 and Prostatic acid phosphatase) and almost none (<1%) expressed TRPM8. CGRPα-GFP+ neurons innervated the dorsal spinal cord and innervated cutaneous and visceral tissues. This included nerve endings in the epidermis and on guard hairs. Our study provides direct evidence that CGRPα+ DRG neurons respond to agonists that evoke pain and itch and constitute a sensory circuit that is largely distinct from nonpeptidergic circuits and TRPM8+/cool temperature circuits. In future studies, it should be possible to conditionally ablate CGRPα-expressing neurons to evaluate sensory and non-sensory functions for these neurons