Adult-Young Ratio, a Major Factor Regulating Social Behaviour of Young: A Horse Study

Adults play an important role in regulating the social behaviour of young individuals. However, a few pioneer studies suggest that, more than the mere presence of adults, their proportions in social groups affect the social development of young. Here, we hypothesized that aggression rates and social cohesion were correlated to adult-young ratios. Our biological model was naturally-formed groups of Przewalski horses, Equus f. przewalskii, varying in composition.We investigated the social interactions and spatial relationships of 12 one- and two-year-old Przewalski horses belonging to five families with adult-young ratios (AYR) ranging from 0.67 to 1.33. We found striking variations of aggression rates and spatial relationships related to the adult-young ratio: the lower this ratio, the more the young were aggressive, the more young and adults segregated and the tighter the young bonded to other young.This is the first study demonstrating a correlation between adult-young ratios and aggression rates and social cohesion of young individuals in a naturalistic setting. The increase of aggression and the emergence of social segregation in groups with lower proportions of adults could reflect a related decrease of the influence of adults as regulators of the behaviour of young. This social regulation has both theoretical and practical implications for understanding the modalities of the influence of adults during ontogeny and for recommending optimal settings, as for instance, for schooling or animal group management

Investigating determinants of yawning in the domestic (Equus caballus) and Przewalski (Equus ferus przewalskii) horses

International audienceYawning is rare in herbivores which therefore may be an interesting group to disentangle the potential function(s) of yawning behaviour. Horses provide the opportunity to compare not only animals living in different conditions but also wild versus domestic species. Here, we tested three hypotheses by observing both domestic and Przewalski horses living in semi-natural conditions: (i) that domestic horses may show an elevated rate of yawning as a result of the domestication process (or as a result of life conditions), (ii) that individuals experiencing a higher level of social stress would yawn more than individuals with lower social stress and (iii) that males would yawn more often than females. The study involved 19 Przewalski horses (PHs) and 16 domestic horses (DHs) of different breeds living in large outdoor enclosures. The results showed that there was no difference between the PH and DH in yawning frequency (YF). PHs exhibited much higher levels of social interactions than DHs. There was a positive correlation between yawning frequency and aggressive behaviours in PHs, especially males, supporting the idea that yawning may be associated with more excitatory/stressful social situations. A correlation was found between yawning frequency and affiliative behaviours in DHs, which supports the potential relationship between yawning and social context. Finally, the entire males, but not castrated males, showed much higher levels of yawning than females in both species. The intensity (rather than the valence) of the interaction may be important in triggering yawning, which could therefore be a displacement activity that helps reduce tension

Can ethograms be automatically generated using body acceleration data from free-ranging birds?

An ethogram is a catalogue of discrete behaviors typically employed by a species. Traditionally animal behavior has been recorded by observing study individuals directly. However, this approach is difficult, often impossible, in the case of behaviors which occur in remote areas and/or at great depth or altitude. The recent development of increasingly sophisticated, animal-borne data loggers, has started to overcome this problem. Accelerometers are particularly useful in this respect because they can record the dynamic motion of a body in e.g. flight, walking, or swimming. However, classifying behavior using body acceleration characteristics typically requires prior knowledge of the behavior of free-ranging animals. Here, we demonstrate an automated procedure to categorize behavior from body acceleration, together with the release of a user-friendly computer application, “Ethographer”. We evaluated its performance using longitudinal acceleration data collected from a foot-propelled diving seabird, the European shag, Phalacrocorax aristotelis. The time series data were converted into a spectrum by continuous wavelet transformation. Then, each second of the spectrum was categorized into one of 20 behavior groups by unsupervised cluster analysis, using k-means methods. The typical behaviors extracted were characterized by the periodicities of body acceleration. Each categorized behavior was assumed to correspond to when the bird was on land, in flight, on the sea surface, diving and so on. The behaviors classified by the procedures accorded well with those independently defined from depth profiles. Because our approach is performed by unsupervised computation of the data, it has the potential to detect previously unknown types of behavior and unknown sequences of some behaviors

Effect of chloroquine on phagolysosomal fusion in cultured guinea pig alveolar macrophages: Implications in drug delivery

The aim of this study was to evaluate the effects of chloroquine on phagolysosomal fusion (PLF) in cultured guinea pig alveolar macrophages (AMs). This technique may be of significance for antitubercular drugs, because the survival of Mycobacterium tuberculosis is linked to evasion of PLF. Guinea pig AMs were obtained from anesthetized animals after exsanguination. The AMs were cultured at a density of 1×106 cell/mL in 24-well plates after attachment to 13-mm coverslips. Culture conditions were at 37°C, with 95% air/5% CO2 in Roswell Park Memorial Institute (RPMI) 1640 medium with 10% heat-inactivated fetal bovine serum. Rhodamine-dextran (70 kd) was incubated with the cells at 0.25 mg/mL for 24 hours to label the lysosomes. Chloroquine treatment where indicated was performed at 10–20 μ g/mL for 1 hour. Fluorescent BioParticles were then added, and PLF was monitored by formation of an organge-yellow fluorescence on fusion of green fluorescent BioParticles with rhodamine-labeled lysosomes. PLF endpoints were measured by scoring for the percentage of orange-yellow cells in the field of view. Image analysis to measure the intensity of the orange-yellow color was performed by obtaining a, b values for 5×5 pixel areas using the Photo Adobe program 4.0.1

In vivo release kinetics of octreotide acetate from experimental polymeric microsphere formulations using oil/water and oil/oil processes

The purpose of the present study was to characterize the in vivo release kinetics of octreotide acetate from microsphere formulations designed to minimize peptide acylation and improve drug stability. Microspheres were prepared by a conventional oil/wate (o/w) method or an experimental oil/oil (o/o) dispersion technique. The dosage forms were administered subcutaneously to a rat animal model, and serum samples were analyzed by radioimmunoassay over a 2-month period. An averaged kinetic profile from each treatment group, as a result, was treated with fractional differential equations. The results indicated that poly(l-lactide) microspheres prepared by the o/o dispersion technique provided lower area under the curve (AUC) values during the initial diffusion-controlled release phase, 7.79 ng×d/mL, versus 75.8 ng/sxd/mL for the o/w batch. During the subsequent erosion-controlled release phase, on the other hand, the o/o technique yielded higher AUC values, 123 ng×d/mL, versus 42.2 ng×d/mL for the o/w batch. The differences observed between the 2 techniques were attributed to the site of drug incorporation during the manufacturing process, given that microspheres contain both porous hydrophilic channels and dense hydrophobic matrix regions. An o/o dispersion technique was therefore expected to produce microspheres with lower incorporation in the aqueous channels, which are responsible for diffusion-mediated drug release

Perspectives for regulating 10 nm particle number emissions based on novel measurement methodologies

Concerns regarding noxious emissions from internal combustion engines have increased over the years. There is a strong need to understand the nature of sub-23 nm particles and to develop measurement techniques to evaluate the feasibility of new regulations for particle number emissions in the sub-23 nm region (down to at least 10 nm). This paper presents the results of three EU-funded projects (DownToTen, PEMs4Nano and SUREAL-23) which supported the understanding, measurement and regulation of particle emissions below 23 nm and have successfully developed sub-23 nm particle measurement devices, specifically laboratory systems and mobile devices for RDE tests. The new technology was validated in chassis dyno tests and on the real road. The results show that sub-23 nm particles are mainly generated at the engine start and during acceleration phases. The innovations show that the technology is mature and robust enough to serve as a basis for regulating sub-23 nm particles.The DownToTen project has received funding from the European Union's Horizon 2020 research and innovation programme under agreement No 724085. The PEMs4Nano project has received funding from the European Union's Horizon 2020 research and innovation programme under agreement No 724145. The SUREAL-23 project has received funding from the European Union's Horizon 2020 research and innovation programme under agreement No 724136