Corticosterone: foraging and fattening puppet master in pre-breeding greylag geese.

Reproduction is one of the most energetically costly life history stages, which impose constraints, even outside the breeding period. Capital breeders typically accumulate energy in preparation for reproduction and the amount of body mass gain prior to reproduction partly determines reproductive outcome in such species. Understanding the physiological and behavioral interplay that governs energy storage is thus essential. Pleiotropic hormones such as glucocorticoids can modulate diel and seasonal energy allocation in vertebrates. Baseline corticosterone (CORT, the main glucocorticoid hormone in birds) fluctuation can induce changes in foraging behavior and/or energy storage. In this experiment, we slightly elevated CORT levels and monitored body mass and foraging behavior prior to reproduction in semi-captive greylag geese. Birds treated either with CORT or placebo pellets inserted subcutaneously were monitored during 21 days. Same individuals were sequentially submitted to both treatments. The increase of CORT levels measured in blood samples confirmed the slight CORT elevation in treated birds. Foraging behaviors increased (up to 9%) in the CORT treated group compared to controls only during morning observations. Birds treated with CORT increased their body mass gain by 6.3% compared to controls. This effect lasted during the first 11 days after pellet implementation. We thus confirm the central role of glucocorticoids on foraging behaviors and body mass gain in pre-nesting birds. This study opens new avenues to manipulate body condition in large-bird species.

Variable response to electric shark deterrents in bull sharks, Carcharhinus leucas.

Although relatively rare, human-shark interactions and sharks bites are increasing globally, which has led to the development of various mitigation measures. Electric shark deterrents (ESDs) have, so far, been the most effective personal deterrents, but have only been scientifically tested on one of the species most frequently responsible for shark bites, i.e. white shark (Carcharodon carcharias). We tested the effectiveness of five ESDs (E-Shark Force, NoShark, Rpela v2, Freedom + Surf, Freedom + Surf-Shortboard) on bull sharks, Carcharhinus leucas, over a period of 21 days in September 2019, in New Caledonia. Standardised bait was attached 30 cm below an experimental board that had an active ESD for up to 15 min, or until a bull shark touched the bait or the board. We compared the numbers of baits taken, numbers of passes and reactions around the board, as well as the distance between the sharks and the board among ESDs and against a control board with bait and no active ESD. The Freedom + Surf was the most effective ESD, reducing the amounts of baits taken by 42.3%, while the Rpela v2 and Freedom + Surf-Shortboard also significantly reduced the number of baits taken by 16.5% and 16.2% respectively. Mean distance between sharks and the bait was not affected by the ESDs, but the number of approaches and the proportion of reactions were both significantly higher when the Freedom + Surf was active compared to other ESDs. The effectiveness of all ESDs decreased over time, with the likelihood of the bait being taken increasing and the number of approaches and distance between sharks and the bait decreasing. Our findings show that the ability of ESDs to deter bull shark varies between products, with the Freedom + Surf resulting in the most behavioural changes, followed by the Rpela v2 and Freedom + Surf-Shortboard. However, none of the products tested completely stopped sharks from taking the bait.

Mean platelet volume: comparison of three analysers towards standardization of platelet morphological phenotype.

INTRODUCTION: The aim of this study was to show variability in the measurement of the mean platelet volume (MPV) depending on the instrument used. METHODS: This prospective analysis was carried out to measure MPV with three instruments, in 30 healthy controls and 113 hospital patients. RESULTS: Firstly, for values in the normal range, the values obtained with the Siemens Advia(®) 2120 are lower than those given by the Beckman Coulter LH750(®) (-0.89), which are in turn lower than those obtained with the Sysmex XE-2100D(®) (-1.11), which represents a 20-25% variation in the measurement. These results emphasize the lack of universal external calibration for MPV analysis and thus make any intercentre comparison of MPV impossible unless the automated haematology analyser used is indicated. Secondly, we stress the differences in behaviour of the instruments in the presence of abnormally large platelets, i.e. an underestimate of the platelet count and the MPV may be provided because instruments using impedance technology may fail to take into account these platelets, but they rightly flag them. CONCLUSION: To harmonize our procedures, we propose definitions of platelet size (normal size, macroplatelets and giant platelets) based on the coordinated interpretation of the MPV, the distribution of platelet volume and the morphological appearance.

Telomerase inhibitors based on quadruplex ligands selected by a fluorescence assay.

The reactivation of telomerase activity in most cancer cells supports the concept that telomerase is a relevant target in oncology, and telomerase inhibitors have been proposed as new potential anticancer agents. The telomeric G-rich single-stranded DNA can adopt in vitro an intramolecular quadruplex structure, which has been shown to inhibit telomerase activity. We used a fluorescence assay to identify molecules that stabilize G-quadruplexes. Intramolecular folding of an oligonucleotide with four repeats of the human telomeric sequence into a G-quadruplex structure led to fluorescence excitation energy transfer between a donor (fluorescein) and an acceptor (tetramethylrhodamine) covalently attached to the 5' and 3' ends of the oligonucleotide, respectively. The melting of the G-quadruplex was monitored in the presence of putative G-quadruplex-binding molecules by measuring the fluorescence emission of the donor. A series of compounds (pentacyclic crescent-shaped dibenzophenanthroline derivatives) was shown to increase the melting temperature of the G-quadruplex by 2-20 degrees C at 1 microM dye concentration. This increase in T(m) value was well correlated with an increase in the efficiency of telomerase inhibition in vitro. The best telomerase inhibitor showed an IC(50) value of 28 nM in a standard telomerase repeat amplification protocol assay. Fluorescence energy transfer can thus be used to reveal the formation of four-stranded DNA structures, and its stabilization by quadruplex-binding agents, in an effort to discover new potent telomerase inhibitors.

[Urinary lithiasis of medical origin]. / Les lithiases urinaires d'origine médicamenteuse.

Analysis of 22,510 urinary calculi between January 1991 to July 2000 performed by infrared spectroscopy allows for separation of drug-induced urolithiasis into two categories: first, the drugs physically embedded in the stone (n = 238; 1.0 per cent), notably indinavir monohydrate (n = 126; 52.9 per cent), followed by triamterene (n = 43; 18.1 per cent), sulphonamides (n = 29; 12.2 per cent) and amorphous silica (n = 24; 10.1 per cent); second, the category of metabolic nephrolithiasis induced by drugs (n = 140; 0.6 per cent), involving mainly calcium and vitamin D supplementation (n = 56; 40.0 per cent) and carbonic anhydrase inhibitors (n = 33; 23.6 per cent). Composition of the stone depended not only on the inducer drug but also on the metabolic state of the patient. Today, drug-induced stones comprise about 1.6 per cent of all calculi in France. Physical analysis and therapeutic history recall of such patients are the keys to diagnosis. Medical care is based on drug avoidance or dose adjustment with increased diuresis and, if necessary, change in urinary pH.