Circadian clock adjustment to plant iron status depends on chloroplast and phytochrome function

Plant chloroplasts are not only the main cellular location for storage of elemental iron (Fe), but also the main site for Fe, which is incorporated into chlorophyll, haem and the photosynthetic machinery. How plants measure internal Fe levels is unknown. We describe here a new Fe‐dependent response, a change in the period of the circadian clock. In Arabidopsis, the period lengthens when Fe becomes limiting, and gradually shortens as external Fe levels increase. Etiolated seedlings or light‐grown plants treated with plastid translation inhibitors do not respond to changes in Fe supply, pointing to developed chloroplasts as central hubs for circadian Fe sensing. Phytochrome‐deficient mutants maintain a short period even under Fe deficiency, stressing the role of early light signalling in coupling the clock to Fe responses. Further mutant and pharmacological analyses suggest that known players in plastid‐to‐nucleus signalling do not directly participate in Fe sensing. We propose that the sensor governing circadian Fe responses defines a new retrograde pathway that involves a plastid‐encoded protein that depends on phytochromes and the functional state of chloroplasts.     

Drug2ways: Reasoning over causal paths in biological networks for drug discovery

Elucidating the causal mechanisms responsible for disease can reveal potential therapeutic targets for pharmacological intervention and, accordingly, guide drug repositioning and discovery. In essence, the topology of a network can reveal the impact a drug candidate may have on a given biological state, leading the way for enhanced disease characterization and the design of advanced therapies. Network-based approaches, in particular, are highly suited for these purposes as they hold the capacity to identify the molecular mechanisms underlying disease. Here, we present drug2ways, a novel methodology that leverages multimodal causal networks for predicting drug candidates. Drug2ways implements an efficient algorithm which reasons over causal paths in large-scale biological networks to propose drug candidates for a given disease. We validate our approach using clinical trial information and demonstrate how drug2ways can be used for multiple applications to identify: i) single-target drug candidates, ii) candidates with polypharmacological properties that can optimize multiple targets, and iii) candidates for combination therapy. Finally, we make drug2ways available to the scientific community as a Python package that enables conducting these applications on multiple standard network formats.     

Instaneous changes in the radial artery blood flow under different physiological conditions

Using a Doppler pulse flowmeter we measured the blood flow in the radial artery at rest and during physical exercise and various other stimuli (arithmetical calculations, electrical stimulation, deep inspiration). The mean resting flow in the radial artery was 0.66 ml/s. Every stimulus was instantaneously followed by a drop in the blood flow to a minimum value; there was no significant differences between these values. The results demonstrate that the new, non-invasive apparatus can be used to study quick changes in the blood flow not detected by routine non-invasive methods.     

Capillary filtration during postischaemic hyperaemia in human limbs.

The rate of capillary filtration after 5 minutes' ischaemia of the lower limbs was studied in man by the venous occlusive plethysmography method. The measured values were 3 times lower on an average than the control values. Comparison of the plethysmographic curves with isotope recordings after the intravenous administration of In-113m shows that volume changes induced by venous occlusion during reactive hyperaemia take place mainly intravascularly and do not allow any conclusions to be drawn on changes in blood-tissue fluid shifts.     

Metazoan parasites of Engraulis ringens as tools for stock discrimination along the Chilean coast

The value of the metazoan parasites of the anchoveta Engraulis ringens as biological tags for stock discrimination is assessed. Three hundred and fifty-nine specimens, obtained from six landing ports in northern and central Chile (Arica, Antofagasta, Caldera, Coquimbo, Valparaiso and Talcahuano) covering a latitudinal gradient of c . 18°, were analysed. Six metazoan parasite species (three ectoparasites and three endoparasites) were obtained. A correspondence analysis suggested that anchoveta from northern and central Chile are comprised of two stocks. Identification of stocks was largely based on qualitative differences (absence in southern localities of the monogenean Pseudanthocotyloides heterocotyle , a parasite proper of engraulids, and the copepod Caligus sp.) and quantitative differences in the prevalence of infection for the remaining species. Inertia and mass value for the correspondence analysis supported the hypothesis of two stocks.     

Immobilized cells: behaviour of carrageenan entrapped yeast during continuous ethanol fermentation

Summary Data of cell concentration, viability and microscopic observation of cell distribution inside carrageenan immobilized yeast beads are reported. Results were obtained from a continuous packed-bed reactor performing alcoholic fermentation and the main observations made on cell activity are in agreement with the fermentation profiles inside the fermenter.