Airborne microplastics detected in the lungs of wild birds in Japan

Microplastics (MPs) have been found in a wide range of animal species including humans. The detection of MPs in human lungs suggests that humans inhale airborne microplastics (AMPs). Although birds respire more efficiently than mammals and are therefore more susceptible to air pollution, little is known about their inhalation exposure to MPs. In this study, we analyzed samples isolated from the lungs of several species of wild birds in Japan by attenuated total reflection (ATR) imaging method of micro-Fourier transform infrared (μFTIR) spectroscopy to clear whether AMPs can be inhaled and accumulate within the lungs of wild birds. To isolate MPs from lung samples of rock doves (Columba livia), black kites (Milvus migrans), and barn swallows (Hirundo rustica) euthanized for pest control, digestion and density separation were performed. After each sample collected on an alumina filter was measured by ATR imaging method using μFTIR spectroscopy, the physical and chemical characteristics of the detected MPs were evaluated. Six MPs were detected in 3 of 22 lung samples. Polypropylene and polyethylene were found in rock doves and ethylene vinyl acetate was found in a barn swallow. Most MPs were fragments of 28.0-70.5 μm. Our results demonstrated that in addition to dietary sources, some wild birds are exposed to MPs by inhalation, and these MPs reach the lungs.

Cervical air sac oxygen profiles in diving emperor penguins: parabronchial ventilation and the respiratory oxygen store

Some marine birds and mammals can perform dives of extraordinary duration and depth. Such dive performance is dependent on many factors, including total body oxygen (O2) stores. For diving penguins, the respiratory system (air sacs and lungs) constitutes 30-50% of the total body O2 store. To better understand the role and mechanism of parabronchial ventilation and O2 utilization in penguins both on the surface and during the dive, we examined air sac partial pressures of O2 (PO2 ) in emperor penguins (Aptenodytes forsteri) equipped with backpack PO2  recorders. Cervical air sac PO2  values at rest were lower than in other birds, while the cervical air sac to posterior thoracic air sac PO2  difference was larger. Pre-dive cervical air sac PO2  values were often greater than those at rest, but had a wide range and were not significantly different from those at rest. The maximum respiratory O2 store and total body O2 stores calculated with representative anterior and posterior air sac PO2  data did not differ from prior estimates. The mean calculated anterior air sac O2 depletion rate for dives up to 11 min was approximately one-tenth that of the posterior air sacs. Low cervical air sac PO2  values at rest may be secondary to a low ratio of parabronchial ventilation to parabronchial blood O2 extraction. During dives, overlap of simultaneously recorded cervical and posterior thoracic air sac PO2  profiles supported the concept of maintenance of parabronchial ventilation during a dive by air movement through the lungs.

Protective roles of free avian respiratory macrophages in captive birds

In the mammalian lung, respiratory macrophages provide front line defense against invading pathogens and particulate matter. In birds, respiratory macrophages are known as free avian respiratory macrophages (FARM) and a dearth of the cells in the avian lung has been purported to foreordain a weak first line of pulmonary defense, a condition associated with high mortality of domestic birds occasioned by respiratory inflictions. Avian pulmonary mechanisms including a three tiered aerodynamic filtration system, tight epithelial junctions and an efficient mucociliary escalator system have been known to supplement FARM protective roles. Current studies, however, report FARM to exhibit an exceptionally efficient phagocytic capacity and are effective in elimination of invading pathogens. In this review, we also report on effects of selective synthetic peroxisome proliferator activated receptor gamma (PPAR γ) agonists on non phlogistic phagocytic properties in the FARM. To develop effective therapeutic interventions targeting FARM in treatment and management of respiratory disease conditions in the poultry, further studies are required to fully understand the role of FARM in innate and adaptive immune responses.