Generation of reactive oxygen responses by monotreme and marsupial granulocytes

The granules of circulating leukocytes contain reactive oxygen species that are important components of host defence against bacterial invasion. We report the capacity of marsupials and monotremes to mount such a defence in a manner similar to their eutherian relatives. Using the nitroblue tetrazolium (NBT) test, reactive oxygen species were detected in the peripheral blood cells of five captive marsupial species (the tammar wallaby, Macropus eugenii, the Rufous hare wallaby, Lagorchestes hirsutus, the Brush-tailed bettong, Bettongia penicillata, the Long-footed potoroo, Potorous longipes, and the Long-nosed potoroo, Potorous tridactylus). The study included animals that were clinically healthy and those that were affected by mycobacterial disease. Animals in poor health elicited weak responses, consistent with the NBT test being used as a diagnostic assay for immunodeficiency. The NBT slide assay was also applied to platypus (Ornithorhyncus anatinus) and short-beaked echidna (Tachyglossus aculeatus) granulocytes to confirm the applicability of the test to this unique group of mammals

The chemistry of protoplanetary fragments formed via gravitational instabilities

In this paper, we model the chemical evolution of a 0.25 M⊙ protoplanetary disc surrounding a 1 M⊙ star that undergoes fragmentation due to self-gravity. We use smoothed particle hydrodynamics including a radiative transfer scheme, along with a time-dependent chemical evolution code to follow the composition of the disc and resulting fragments over approximately 4000 yr. Initially, four quasi-stable fragments are formed, of which two are eventually disrupted by tidal torques in the disc. From the results of our chemical modelling, we identify species that are abundant in the fragments (e.g. H2O, H2S, HNO, N2, NH3, OCS, SO), species that are abundant in the spiral shocks within the disc (e.g. CO, CH4, CN, CS, H2CO) and species that are abundant in the circumfragmentary material (e.g. HCO+). Our models suggest that in some fragments it is plausible for grains to sediment to the core before releasing their volatiles into the planetary envelope, leading to changes in, e.g., the C/O ratio of the gas and ice components. We would therefore predict that the atmospheric composition of planets generated by gravitational instability should not necessarily follow the bulk chemical composition of the local disc material