Cryptococcus neoformans Thermotolerance to Avian Body Temperature Is Sufficient For Extracellular Growth But Not Intracellular Survival In Macrophages

Cryptococcus neoformans is a fatal fungal pathogen of humans that efficiently parasitises macrophages. Birds can be colonised by cryptococci and can transmit cryptococcosis to humans via inhalation of inoculated bird excreta. However, colonisation of birds appears to occur in the absence of symptomatic infection. Here, using a pure population of primary bird macrophages, we demonstrate a mechanism for this relationship. We find that bird macrophages are able to suppress the growth of cryptococci seen in mammalian cells despite C. neoformans being able to grow at bird body temperature, and are able to escape from bird macrophages by vomocytosis. A small subset of cryptococci are able to adapt to the inhibitory intracellular environment of bird macrophages, exhibiting a large cell phenotype that rescues growth suppression. Thus, restriction of intracellular growth combined with survival at bird body temperature explains the ability of birds to efficiently spread C. neoformans in the environment whilst avoiding systemic disease

Discovery of an Eo-Meso-Neoarchean Terrane in the East Greenland Caledonides

tThis study investigates basement gneisses from the Niggli Spids thrust sheet of the East Greenland Caledonides in an attempt to place them into the broader context of the Archean–Paleoproterozoicarchitecture of the Greenland shield. Our combined whole-rock geochemical and U–Pb zircon geochronol-ogy results from Gåseland reveal an Archean terrane defined by TTG magmatic events at 3607 Ma and3070–2980 Ma followed by metamorphism and high-K granite intrusion at 2790–2677 Ma. These results identify a relatively pristine Archean terrane with previously unknown Eoarchean rocks that holds poten-tial for future investigations into the early evolution of continental crust, and adds to a growing body of data characterizing the Archean–Paleoproterozoic architecture of East Greenland