Experimental reduction in blood oxygen-carrying capacity alters foraging behaviour in a colonial waterbird.

Oxidative metabolism is a key component of organismal physiology and it is primarily determined by aerobic capacity, which depends on the capacity of blood to carry oxygen. However, experimental manipulations of blood oxygen-carrying capacity are rarely implemented to test ecophysiological hypotheses in vertebrate populations. Here, we combined an experimental manipulation of blood oxygen-carrying capacity with GPS tracking to test whether suboptimal (reduced) haematological performance affects foraging behaviour in a colonial waterbird, the black-headed gull, Chroicocephalus ridibundus. First, a validation of phenylhydrazine (PHZ) treatment in gulls revealed a 9-18% reduction in haematocrit and blood haemoglobin concentration (via oxidative denaturation and haemolysis of erythrocytes). Then, GPS tracking of experimental (PHZ-treated) and control (saline-treated) gulls during the incubation period provided no support for reduced or suspended engagement in energetically costly activities (long-distance foraging trips) by experimental birds. Instead, we found evidence for fine-scale alterations in foraging behaviour of PHZ-treated individuals, which resulted in fewer foraging trips per unit time, but trips that were longer in duration and distance compared with those of control birds. This suggests reduced foraging performance of experimental birds (e.g. lower capacity to find and collect food during trips) or evasion of social competition, although no differences in the total investment in foraging may also suggest compensatory physiological responses to haemolytic anaemia. Our study contributes to a better understanding of the physio-ecological nexus in non-diving colonial avian species. Whether behavioural effects of reduced aerobic capacity have any implications for gull condition and reproductive performance should be the subject of further investigation.

Morphological ontogeny of Hermanniella septentrionalis (Acari, Oribatida, Hermanniellidae) and comments on Hermanniella Berlese.

The morphological ontogeny of Pilogalumna tenuiclava (Berlese, 1908) is redescribed and illustrated. The prodorsal setae of juveniles are of medium size or long and barbed, and bothridial seta is fusiform, with thick, barbed head. Larva has 11 pairs of gastronotal setae, including h2, most are short and smooth, except for longer and barbed c2, c3, dp, h1 and h2. The nymphs have 15 pairs of these setae, most are short and smooth, except for longer and barbed c3. Gastronotal shield of juveniles is poorly developed, with setae of d-, l-series, and h1 in the larva, and d-, l-, h-series and p1 in the nymphs, setae of c-series, p2 and p3 are inserted on unsclerotized integument. In all juveniles, a humeral organ is present.

Prevalence and Antibiotic Resistance of Campylobacter spp. in Urban and Rural Black-Headed Gulls Chroicocephalus ridibundus.

We investigate the role of black-headed gulls (Chroicocephalus ridibundus), an omnivorous species that is among the most likely wild bird candidates for transmission of zoonotic agents, as a potential reservoir of Campylobacter spp. Colonies with different anthropogenic pressures were studied to examine differences in exposure to sources of Campylobacter between rural and urban birds. We recorded Campylobacter spp. in 4.87% of adult black-headed gulls and 2.22% of their chicks after analysing 1036 cloacal swabs collected over two breeding seasons in three colonies in northern Poland. Campylobacter jejuni was found most frequently (85.72%), and Campylobacter lari and Campylobacter coli were much scarcer. Prevalence of Campylobacter did not differ significantly between black-headed gulls breeding in urban (4.27%) and rural (3.80%) habitats. Almost all isolates from chicks and adults were susceptible to azithromycin (97.62%) and erythromycin (95.24%), but fewer to tetracycline (50.00%) and ciprofloxacin (47.62%). Campylobacter prevalence was unrelated to the date of sampling. Our study indicates that black-headed gulls are carriers of resistant to antibiotics Campylobacter and they can contaminate natural waterbodies with their faeces, which poses a threat to human and farm animal health.

Density-dependence of nestling immune function and physiological condition in semi-precocial colonial bird: a cross-fostering experiment.

BACKGROUND: Nesting in large aggregations provides several important advantages for colonially breeding birds. However, it also imposes certain costs, associated with facilitated pathogen transmission and social stress. The cost-benefit ratio is not similar for all the birds in a colony and it might be mediated by nest density. To investigate the influence of nest density on cell-mediated immune function and on physiological condition of nestlings, we arranged a cross-fostering experiment in three breeding colonies of black-headed gulls Chroicocephalus ridibundus. First, we exchanged eggs between plots of high and low nest density. Afterwards, we performed phytohaemagglutinin (PHA) skin test and we measured blood haemoglobin concentration in nearly 350 nestlings from experimental (exchanged) and control (non-exchanged) groups. RESULTS: We found that PHA response was lowest in high nest density control group, indicating that depressed immune function of offspring, likely caused by social stress, can be considered as a cost of colonial breeding. Contrastingly, body condition of nestlings was the poorest in low density control group. CONCLUSION: Nestlings hatched and raised in high nest density plots did not have higher blood haemoglobin concentration in comparison to other study groups. Furthermore, they were affected with depressed cell mediated immune function, which is possibly driven by combined maternal (corticosteroid hormones deposited in yolk) and environmental (elevated social stress) effects. These results indicate that breeders from high nest densities do not benefit by rising offspring in better quality, in terms of immune function and body condition, although, in the light of previous studies, high nest densities are occupied by birds of higher individual quality, than low density areas. Our study provides a novel insight into the mechanisms of density-dependence that govern fitness of colonially nesting birds.

Intercolony variation in foraging flight characteristics of black-headed gulls Chroicocephalus ridibundus during the incubation period.

Using GPS loggers, we examined the influence of colony, sex, and bird identity on foraging flight characteristics of black-headed gulls Chroicocephalus ridibundus during the incubation period. We studied tracks of 36 individuals breeding in one urban and two rural colonies in Poland. Birds from both rural colonies performed the furthest flights (mean max distance 8-12 km, up to 27 km) foraging mainly in agricultural areas. Gulls from the urban colony performed shorter flights (mean 5 km, up to 17 km) visiting mainly urbanized areas and water bodies. We found that females performed longer flights and their flight parameters were less repeatable compared to males. Males from both rural colonies visited water bodies more frequently than females. In all colonies, males (but not females) used habitats unproportionally to their availability in the vicinity. Relatively low interindividual and relatively high intraindividual overlap in home ranges indicated considerable foraging site fidelity. Individuals specialized in the use of a particular type of habitat performed shorter foraging flights compared to individuals using diverse habitats during their foraging flights. Our results indicate diverse foraging strategies of black-headed gulls, including generalists that explore various habitats and specialists characterized by high foraging site and habitat fidelity.

Proxy Users Enable Older People Creative Writing on the Web.

This paper presents several state-of-the-art concepts within Internet studies and applies them to the creative writing of older people using the Internet. For more than 10 years two creative Web users aged 80+, assisted by younger proxy users, were involved in preliminary action research. It was aimed at finding patterns of inducing older people's creativity and sharing their wisdom with the general Internet audience. The effectiveness of conducted action research in transferring wisdom using silver digital content is high. It is demonstrated with (a) qualitative participants' insights, (b) the quantitative description of statistics of blog visits, and (c) the social significance of the topics covered in the created content. Lasting for more than a decade and located within the space of socio-technological solutions in Central and Eastern Europe, the results delivered patterns of emerging technologies aimed at enhancing older people's creativity on the Web. The insights from those two action-based case studies enabled the development of new hypotheses. New directions of further, more advanced research of older users' activity are based on interdisciplinary studies at the crossroads of public health, sociological theory, gerontology, and human-computer interaction studies. New research questions are presented, to be explored within the social scientific studies of the next-generation Internet. Departing from the established concepts and preliminary research, the authors hypothesize that: (1) in order to optimize non-human technology-based assistants, human proxy users should be researched; (2) voice assistant technology could become the primary proxy for a production of silver digital content; and (3) interactive and intelligent technology will be the substitute for social actors that prevent exclusion and disengagement. The remaining research question also refers to the conditions under which the technology can be a viable substitute for proxy users.

Macrocyclic Metal Complex-DNA Conjugates for Electrochemical Sensing of Single Nucleobase Changes in DNA.

The direct incorporation of macrocyclic cyclidene complexes into DNA via automated synthesis results in a new family of metal-functionalized DNA derivatives that readily demonstrate their utility through the ability of one redox-active copper(II)-containing strand to distinguish electrochemically between all four canonical DNA nucleobases at a single site within a target sequence of DNA.

Face-to-face dinuclear scaffolds composed of tetraazamacrocyclic charged and neutral complexes.

A new family of bismacrocyclic homo- and heteronuclear Ni and Cu complexes has been synthesized and characterized. The ligand scaffold is comprised of two 14-membered tetraazamacrocyclic sites held in cofacial orientation. The dinuclear complexes are unique in that one macrocyclic center is neutral while the other one is charged, although the ligand backbones are nearly identical. This leads to a binuclear system of two structurally similar components, differing in their electron-donor abilities. The crystallographically characterized structures in the solid state revealed similarity of the four dinuclear complexes studied. The metal-metal separations are between 4 and 5 A. The strongest electrostatic intramolecular interactions occur in the molecules with neutral and charged components, most differing in donor abilities.

Neutral nickel(II) and copper(II) tetraazamacrocyclic complexes as molecular rods attached to gold electrodes.

New dithiolated derivatives of neutral Cu(II) and Ni(II) tetraazamacrocyclic complexes have been synthesized and characterized by spectroscopic and diffractional methods. These rod-shaped molecules were assembled in monocomponent and mixed monolayers on gold electrodes. In the mixed monolayers, the active molecules were embedded in a hexanethiol matrix. The dithiolated complexes are oriented perpendicularly to the electrode, and reveal faster kinetics of electron transfer than those assembled in a single-component monolayer. They appear as protrusions, which are easily addressed by using the STM method. In the presence of a suitable electron acceptor in the solution, the donor properties of the anchored Cu complex were weakened, which revealed donor-acceptor interactions with the monolayer. The peak position in the voltammogram indicates a stronger interaction of the solution-based acceptor with the reduced Cu(II) form than with the Cu(III) complex. This suggests the possibility of switching the association on or off by applying an appropriate potential.

Fine-tuning of properties of bismacrocyclic dinuclear cyclidene receptors by N-methylation.

N-Methylated bismacrocyclic Cu and Ni complexes were synthesised and structurally characterised in the solid state. Their properties in solution were analysed by using NMR and ESR spectroscopies and electrochemical methods. Face-to-face biscyclidenes linked through polymethylene chains form rectangular boxlike cations. These moieties can host some small guest molecules (water, pi-electron donating compounds) and are stabilised by a shell of neighbouring counterions. For the bismacrocyclic dinuclear complexes containing two nickel or two copper ions, the intramolecular interactions between the metallic centres are strengthened through methylation of the macrocyclic components, as compared with the nonmethylated species. We report the electron coupling created by two unpaired electrons coming from two copper centres observed by ESR spectroscopy. Methylation weakens the electron-acceptor properties of the complexes, which leads to less effective binding of the pi-electron-donating guests. It also increases the stability of the lower oxidation states. In the case of the copper complexes, both Cu(II)/Cu(I) and Cu(II)/Cu(III) reversible one-electron transfers are seen in the voltammograms. These changes in properties are interpreted as the consequences of steric repulsion between the methyl substituents and the macrocyclic ring.