Kevin D. McKeegan

TL;DR: In this article, ion-microprobe measurements of the carbon-isotope composition of carbonaceous inclusions within grains of apatite (basic calcium phosphate) from the oldest known sediment sequences a approx. 3,800 Myr-old banded iron formation from the Isua supracrustal belt, West Greenland and a similar formation from Akilia island that is possibly older than 3,850 Myr.

TL;DR: These results demonstrate the feasibility of simultaneous determination of the identity and the metabolic activity of naturally occurring microorganisms and indicate assimilation of isotopically light methane into specific archaeal cells.

TL;DR: The Stardust spacecraft collected thousands of particles from comet 81P/Wild 2 and returned them to Earth for laboratory study, and preliminary examination shows that the nonvolatile portion of the comet is an unequilibrated assortment of materials that have both presolar and solar system origin.

TL;DR: The results provide direct evidence for the involvement of at least two distinct archaeal groups (ANME-1 and ANME-2) in AOM at methane seeps and indicate that the microbial species and biotic interactions mediating anaerobic methanotrophy are diverse and complex.

TL;DR: Hydrogen, carbon, nitrogen, and oxygen isotopic compositions are heterogeneous among comet 81P/Wild 2 particle fragments; however, extreme isotopic anomalies are rare, indicating that the comet is not a pristine aggregate of presolar materials.