Do Tengmalm’s Owls alter parental feeding effort under varying conditions of main prey availability?

We studied the diet composition and behavioural responses to variable food conditions in Tengmalm’s Owls (Aegolius funereus). The abundance of main prey (voles and mice) of owls was higher in the Ore Mountains, Czech Republic, than in the Kauhava region, Finland. We monitored nests continuously by a camera system to estimate the feeding frequency and to identify prey items provided to nestlings. We recorded 990 prey deliveries at six nests in the Ore Mountains and 1,679 prey deliveries at nine nests in the Kauhava region. Mice (Apodemus) and voles (Microtus and Clethrionomys) were the main foods of owls in the Ore Mountains, whereas voles (Clethrionomys and Microtus) and shrews (Sorex) were the main foods in the Kauhava region. In consequence, on average smaller prey items were brought to nestlings at the Finnish site. However, both absolute and relative (per one nestling) feeding frequency was higher in the Kauhava region, and the biomass available to individual nestlings did not differ between the two areas. Moreover, the Finnish and Czech pairs produced about the same number of fledglings. Our results suggest that male owls are able to maintain the amount of food required for chicks by switching to alternative prey, and to increase their prey delivery rates under conditions of reduced abundance of main food.     

Species‐specific limitation of vole population growth by least weasel predation: facilitation of coexistence?

Interspecific competition is usually understood as different species competing directly with each other for limited resources. However, predators can alter such competitive interactions substantially. Predation can promote the coexistence of species in a situation where it would otherwise be impossible, for example if a tradeoff between the competitive abilities and predation resistance of the prey species exists. The field vole Microtus agrestis and the sibling vole M. rossiaemeridionalis are sympatric grassland species, which compete for the same resources. At the population level sibling voles are suggested to be superior competitors to field voles, yet more vulnerable to predation. We tested the effects of predation on the two species in 0.5 ha outdoor enclosures by exposing vole populations to radio-collared freely-hunting least weasels Mustela nivalis nivalis for three weeks. Lethal and non-lethal impacts of predation limited population densities of both species during and after the experimental period, but the effect was more pronounced in sibling voles in which population densities decreased markedly during the treatment period and even after that. Field vole population densities remained stable under weasel predation, while densities increased in controls. Survival in both species was lower in treatment populations compared to controls, but the effect tended to be more pronounced in sibling voles and in females of both species. The average mass of adults in both species declined in the treatment populations. These results suggest that predation by least weasels can limit vole populations locally, even during favourable summer conditions, and have extended negative effects on the dynamics of vole populations. In addition, predation alleviated interspecific competition between the vole species and is, therefore, a potential factor enabling the coexistence of them.     

AtRLI2 is an Endogenous Suppressor of RNA Silencing

RNA silencing is a mechanism involved in gene regulation during development and anti-viral defense in plants and animals. Although many viral suppressors of this mechanism have been described up to now, this is not the case for endogenous suppressors. We have identified a novel endogenous suppressor in plants: RNase L inhibitor (RLI) of Arabidopsis thaliana. RLI is a very conserved protein among eukaryotes and archaea. It was first known as component of the interferon-induced mammalian 2′–5′ oligoadenylate (2–5A) anti-viral pathway. This protein is in several organisms responsible for essential functions, which are not related to the 2–5A pathway, like ribosome biogenesis and translation initiation. Arabidopsis has two RLI paralogs. We have described in detail the expression pattern of one of these paralogs (AtRLI2), which is ubiquitously expressed in all plant organs during different developmental stages. Infiltrating Nicotiana benthamiana green fluorescent protein (GFP)-transgenic line with Agrobacterium strains harboring GFP and AtRLI2, we proved that AtRLI2 suppresses silencing at the local and at the systemic level, reducing drastically the amount of GFP small interfering RNAs.     

Scaling-up from an implementation trial to state-wide coverage: results from the preliminary Melbourne Diabetes Prevention Study

ABSTRACT: BACKGROUND: The successful Greater Green Triangle Diabetes Prevention Program (GGT DPP), a small implementation trial, has been scaled-up to the Victorian state-wide 'Life!' programme with over 10,000 individuals enrolled. The Melbourne Diabetes Prevention Study (MDPS) is an evaluation of the translation from the GGT DPP to the Life! programme. We report results from the preliminary phase (pMDPS) of this evaluation. METHODS: The pMDPS is a randomised controlled trial with 92 individuals aged 50 to 75 at high risk of developing type 2 diabetes randomised to Life! or usual care. Intervention consisted of six structured 90-minute group sessions: five fortnightly sessions and the final session at 8 months. Participants underwent anthropometric and laboratory tests at baseline and 12 months, and provided self-reported psychosocial, dietary, and physical activity measures. Intervention group participants additionally underwent these tests at 3 months. Paired t tests were used to analyse within-group changes over time. Chi-square tests were used to analyse differences between groups in goals met at 12 months. Differences between groups for changes over time were tested with generalised estimating equations and analysis of covariance. RESULTS: Intervention participants significantly improved at 12 months in mean body mass index ([MINUS SIGN]0.98 kg/m2, standard error (SE) = 0.26), weight ([MINUS SIGN]2.65 kg, SE = 0.72), waist circumference ([MINUS SIGN]7.45 cm, SE = 1.15), and systolic blood pressure ([MINUS SIGN]3.18 mmHg, SE = 1.26), increased high-density lipoprotein-cholesterol (0.07 mmol/l, SE = 0.03), reduced energy from total ([MINUS SIGN]2.00%, SE = 0.78) and saturated fat ([MINUS SIGN]1.54%, SE = 0.41), and increased fibre intake (1.98 g/1,000 kcal energy, SE = 0.47). In controls, oral glucose at 2 hours deteriorated (0.59 mmol/l, SE = 0.27). Only waist circumference reduced significantly ([MINUS SIGN]4.02 cm, SE = 0.95).Intervention participants significantly outperformed controls over 12 months for body mass index and fibre intake. After baseline adjustment, they also showed greater weight loss and reduced saturated fat versus total energy intake.At least 5% weight loss was achieved by 32% of intervention participants versus 0% controls. CONCLUSIONS: pMDPS results indicate that scaling-up from implementation trial to state-wide programme is possible. The system design for Life! was fit for purpose of scaling-up from efficacy to effectiveness.Trial registrationAustralian and New Zealand Clinical Trials Registry ACTRN12609000507280.     

Identification of endothelial genes up-regulated in vivo

We have used microarrays to identify genes that are selectively expressed in endothelial cells in vivo. Analysis of freshly isolated endothelial cells from the lungs and kidneys reveals that 350 out of the 10,000 genes represented on the microarrays were expressed at higher levels than by the corresponding parenchymal cells. Thirteen of these genes were identified both in the lung and kidney screens from a subset of about 5000 genes. Many of these genes are known to be specifically expressed in endothelial cells, but about 200 genes were potentially novel endothelial genes. The preferential endothelial expression of a selected group of these genes was confirmed by quantitative polymerase chain reaction or in situ mRNA hybridization. Comparison of the genes expressed in lung and kidney endothelia revealed numerous differences. Notably, genes encoding components of an ephrin signaling pathway were highly expressed in lung endothelial cells. In summary, the genes we have identified represent potentially new pan-endothelial and tissue-specific endothelial markers.     

Regulation of cellular respiration in myoglobin-deficient mouse heart

The regulation of cardiac O2 consumption according to energy demand is best studied in the intact organ by non-destructive methods, using probes detectable by their fluorescence or light absorption. However, myoglobin is normally present in high concentrations and swamps the cytochrome spectra, thereby bringing about an oxygen-dependent internal filter effect which quenches the fluorescence of probes. A viable myoglobin-deficient mouse strain (Myo(-/-)) has been generated previously and isolated perfused Myo(-/-) hearts are used here as an ideal model for studying mitochondrial metabolism by non-destructive optical methods. In this model we monitored the redox state of cytochrome aa3 and flavoprotein (Fp) during perturbations of myocardial work output upon changes in extracellular [Ca2+], KCl-induced arrest and pacing. Increased consumption of energy and O2 led to a concomitant reduction of cytochrome aa3 and oxidation of Fp. Administration of a medium chain-length fatty acid caused a marked reduction of Fp, but even then an increase in energy consumption caused Fp oxidation. The results show that cell respiration in the intact myocardium is regulated at the site of the respiratory chain. Our findings do not support the NMR-based hypothesis that O2 consumption is mainly regulated at the level of intermediary metabolism and by the pressure of reducing equivalents to the mitochondrial respiratory chain.     

Milk and Serum Progesterone Levels in Mares after Ovulation

Twenty-four Finnhorse mares were examined by rectal palpation and ultrasonography every 6 h during late oestrus to determine the time of ovulation. Milk and serum samples were collected every 6 h after the detected ovulation for progesterone analysis. The progesterone rises took place within 0–54 h and 0–60 h after ovulation, in milk and serum, respectively. Statistically significant differences (p < 0.05) in progesterone levels were observed for the first time 12–18 h and 18–24 h after ovulation, in serum and milk, respectively, as compared to progesterone levels 0–6 h after ovulation.     

Ionic Dependence of Membrane Potential and Glutamate Receptor-Linked Responses in Synaptoneurosomes as Measured with a Cyanine Dye, DiS-C2-(5)

Membrane potentials of particles present in a subcellular brain preparation, called synaptoneurosomes, have been monitored by measurement of changes in the absorbance of a cyanine dye, DiS-C2-5. The membrane potential of the particles seems to be dependent on both Cl- and K+ diffusion potentials, as judged from dependence of the absorbance changes on the K+ equilibrium potential across the membrane in the presence of Ba2+ or when Cl- was replaced with gluconate. The apparent high Cl- permeability of the membrane preparation was reduced in the presence of picrotoxin, a finding suggesting endogenous activation of receptor-linked Cl- channels. Glutamate and kainate caused depolarization of the membranes present in the preparation. This effect was only seen if K+ channels had been blocked in the presence of Ba2+ or 4-aminopyridine. No responses were observed with other glutamate receptor agonists (quisqualate or N-methyl-D-aspartate). The membrane potential of particles present in conventional synaptosomal preparations neither had a high Cl- permeability nor reacted to glutamate or kainate in the present conditions. The results suggest that synaptoneurosome preparations may be used for functional studies on postsynaptic neurotransmitter receptor-linked membrane potential changes with optical probes of membrane potential.