concerns that the genes sequenced in 2015 were the result of contamination, or the initial sample being a mix of cells. Imachi and his colleagues grew cells from sediment that had been collected below the sea bed. But why did the cells take so long to grow? The problem in culturing cells from sediment is that most microbes aren't as Escherichia coli obliging as familiar lab workhorses such as . The researchers took up the challenge and with much patience, trial and error, they found that the cells grew best on a diet of peptides, amino acids and even baby-milk powder. The resulting cells are tiny spheres 300 - 750 nanometres in diameter, but they often extrude longer, branched filaments that reach out to meet neighbouring bacteria. The researchers think that such a partnership, both biochemical and physical, could tell us more about the processes that led to the eukaryote cell being formed - a question more researchers must surely try to tackle. Despite the promise of what is to come, a degree of caution is needed. Eukaryotes evolved more than two billion years ago, possibly coincident with an episode of global climatic change called the Great Oxidation Event. Nonetheless, the achievement brings us closer to meeting living relatives of our ancestors. We await the next chapter with anticipation.

Eguchi, J., Seales, J., Dasgupta, R., 2020. Great Oxidation and Lomagundi events linked by deep cycling and enhanced degassing of carbon. Nature Geoscience 13, 71-76.

https://doi.org/10.1038/s41561-019-0492-6 For approximately the first 2 billion years of the Earth's history, atmospheric oxygen levels were extremely low. It was not until at least half a billion years after the evolution of oxygenic photosynthesis, perhaps as early as 3 billion years ago, that o xygen rose to appreciable levels during the Great Oxidation Event. Shortly after, marine carbonates underwent a large positive spike in carbon isotope ratios known as the Lomagundi event. The mechanisms responsible for the Great Oxidation and Lomagundi events remain debated. Using a carbon - oxygen box model that tracks the Earth's surface and interior carbon fluxes and reservoirs, while also tracking carbon isotopes and atmospheric oxygen levels, we demonstrate that about 2.5 billion years ago a tectonic transition that resulted in increased volcanic CO emissions could have led to increased deposition of both 2 carbonates and organic carbon (organic C) via enhanced weathering and nutrient delivery to oceans. Increased burial of carbonates and organic C would h ave allowed the accumulation of atmospheric oxygen while also increasing the delivery of carbon to subduction zones. Coupled with preferential release of carbonates at arc volcanoes and deep recycling of organic C to ocean island volcanoes, we find that su ch a tectonic transition can simultaneously explain the Great Oxidation and Lomagundi events without any change in the fraction of carbon buried as organic C relative to carbonate, which is often invoked to explain carbon isotope excursions.

El Diasty, W.S., Peters, K.E., Moldowan, J.M., Essa, G.I., Hammad, M.M., 2020. Organic geochemistry of condensates and natural gases in the northwest Nile Delta offshore Egypt. Journal of Petroleum Science and Engineering 187, 106819.

http://www.sciencedirect.com/science/article/pii/S0920410519312380 Although recent gas and condensate discoveries have been achieved in the deep ultramarine Nile Delta Basin of northern Egypt, the genetic origin and formation mechanisms of these hydrocarbons remain unclear. Twenty condensate and 34 natural gas samples from Miocene - Pliocene sandstone reservoirs in the northwest Nile Delta offshore Egypt were analyzed to infer their origin, degree of thermal maturity, and extent of alteration. Based on source-related biomarkers, the condensate samples were interpreted to have originated from clay-rich n non-marine source rocks, based on high Pr/Ph, high Ts/Tm, low or absent C -propylcholestanes and high 30 hopane/sterane ratios. The environment of deposition of the source rock is expected to be proximal and likely received high influx of terrigenous-dominated organic matter. Chemometrics of 12 source-related biomarker and isotopic ratios identify six genetic families. Geochemical characterization of the families shows that they