Protein Deimination and Extracellular Vesicle Profiles in Antarctic Seabirds.

Pelagic seabirds are amongst the most threatened of all avian groups. They face a range of immunological challenges which seem destined to increase due to environmental changes in their breeding and foraging habitats, affecting prey resources and exposure to pollution and pathogens. Therefore, the identification of biomarkers for the assessment of their health status is of considerable importance. Peptidylarginine deiminases (PADs) post-translationally convert arginine into citrulline in target proteins in an irreversible manner. PAD-mediated deimination can cause structural and functional changes in target proteins, allowing for protein moonlighting in physiological and pathophysiological processes. PADs furthermore contribute to the release of extracellular vesicles (EVs), which play important roles in cellular communication. In the present study, post-translationally deiminated protein and EV profiles of plasma were assessed in eight seabird species from the Antarctic, representing two avian orders: Procellariiformes (albatrosses and petrels) and Charadriiformes (waders, auks, gulls and skuas). We report some differences between the species assessed, with the narrowest EV profiles of 50-200 nm in the northern giant petrel Macronectes halli, and the highest abundance of larger 250-500 nm EVs in the brown skua Stercorarius antarcticus. The seabird EVs were positive for phylogenetically conserved EV markers and showed characteristic EV morphology. Post-translational deimination was identified in a range of key plasma proteins critical for immune response and metabolic pathways in three of the bird species under study; the wandering albatross Diomedea exulans, south polar skua Stercorarius maccormicki and northern giant petrel. Some differences in Gene Ontology (GO) biological and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways for deiminated proteins were observed between these three species. This indicates that target proteins for deimination may differ, potentially contributing to a range of physiological functions relating to metabolism and immune response, as well as to key defence mechanisms. PAD protein homologues were identified in the seabird plasma by Western blotting via cross-reaction with human PAD antibodies, at an expected 75 kDa size. This is the first study to profile EVs and to identify deiminated proteins as putative novel plasma biomarkers in Antarctic seabirds. These biomarkers may be further refined to become useful indicators of physiological and immunological status in seabirds-many of which are globally threatened.

Sex-specific effects of fisheries and climate on the demography of sexually dimorphic seabirds.

Many animal taxa exhibit sex-specific variation in ecological traits, such as foraging and distribution. These differences could result in sex-specific responses to change, but such demographic effects are poorly understood. Here, we test for sex-specific differences in the demography of northern (NGP, Macronectes halli) and southern (SGP, M. giganteus) giant petrels - strongly sexually size-dimorphic birds that breed sympatrically at South Georgia, South Atlantic Ocean. Both species feed at sea or on carrion on land, but larger males (30% heavier) are more reliant on terrestrial foraging than the more pelagic females. Using multi-event mark-recapture models, we examine the impacts of long-term changes in environmental conditions and commercial fishing on annual adult survival and use two-sex matrix population models to forecast future trends. As expected, survival of male NGP was positively affected by carrion availability, but negatively affected by zonal winds. Female survival was positively affected by meridional winds and El Niño-Southern Oscillation (ENSO), and negatively affected by sea ice concentration and pelagic longline effort. Survival of SGPs did not differ between sexes; however, survival of males only was positively correlated with the Southern Annular Mode (SAM). Two-sex population projections indicate that future environmental conditions are likely to benefit giant petrels. However, any potential increase in pelagic longline fisheries could reduce female survival and population growth. Our study reveals that sex-specific ecological differences can lead to divergent responses to environmental drivers (i.e. climate and fisheries). Moreover, because such effects may not be apparent when all individuals are considered together, ignoring sex differences could underestimate the relative influence of a changing environment on demography.

Successful rehabilitation of Macronectes halli and Macronectes giganteus in southeastern Brazil / Sucesso na reabilitação de Macronectes halli e Macronectes giganteus no sudeste do Brasil

This report describes the successful rehabilitation of two species of pelagic seabirds (Macronectes halli and Macronectes giganteus) rescued on the southern coast of the state of São Paulo, Brazil, and taken to the IPeC rehabilitation center (S25°023258 W-47°928737). Data on the enclosures, diet, clinical management and laboratory tests were detailed during the 75 d of treatment, during which the birds remained at the center. This report demonstrates that a combination of environmental and nutritional management with a proper diagnosis and adequate clinical treatment naturally lead to a shorter period in captivity, which is crucial to the successful rehabilitation of these birds. The enclosures should have visual isolation and animals kept separate from other birds. The form of offering food differs based on the feeding habits and taxon. At the time of release back into the wild, the site chosen should be isolated to enable the bird to feel more secure when taking flight. The present report describes the first record of the rehabilitation and release of these two species in Brazil.(AU)

Este relato descreve a reabilitação bem-sucedida de duas espécies de aves marinhas pelágicas (Macronectes halli e Macronectes giganteus) resgatadas no litoral sul de São Paulo e levadas ao Centro de Reabilitação IPeC (S-25°023258 W-47°928737). As medidas de ambientação dos recintos, dieta, manejo clínico e exames laboratoriais, implementadas nos 75 dias em que as aves permaneceram no Centro, foram detalhadamente descritas. Este relato demonstrou que a combinação de um correto manejo ambiental e nutricional com o diagnóstico e tratamento clínico adequados leva naturalmente à uma brevidade nos dias de cativeiro, todos considerados fatores essenciais para o sucesso na reabilitação dessas aves. Os recintos devem ter isolamento visual, e os animais devem ser mantidos separados de outras aves. A alimentação e a forma de ofertar o alimento variam de acordo com hábitos alimentares e táxon. No momento da soltura, o lugar deve ser isolado, deixando o animal mais seguro para alçar voo. Este relato descreve o primeiro registro de reabilitação e soltura de ambas as espécies no Brasil.(AU)